Time-domain adjustment of phase retardation in a liquid crystal grating for a color display

ABSTRACT

A method includes sequentially transmitting, through a beam steering device, light of a first color and light of a second color that is distinct from the first color. The method also includes applying a first voltage to the beam steering device for transmission of the light of the first color through the beam steering device; and applying a second voltage to the beam steering device for transmission of the light of the second color through the beam steering device. A device configured to perform the method is also described.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/065,772, filed Mar. 9, 2016, which claims the benefit of,and priority to, U.S. Provisional Patent Application Ser. No.62/200,481, filed Aug. 3, 2015 and U.S. Provisional Patent ApplicationSer. No. 62/246,117, filed Oct. 25, 2015. All of these applications areincorporated by reference herein in their entireties. This applicationis related to U.S. patent application Ser. No. 15/347,672, entitled“Wide Angle Beam Steering in Sunglasses for Virtual Reality andAugmented Reality”, filed Nov. 9, 2016, which claims priority to U.S.Provisional Patent Application Ser. No. 62/270,523, filed Dec. 21, 2015,both of which are incorporated by reference herein in their entireties.

TECHNICAL FIELD

This relates generally to display devices, and more specifically tohead-mounted display devices.

BACKGROUND

Head-mounted display devices (also called herein head-mounted displays)are gaining popularity as means for providing visual information touser. In head-mounted displays, optical elements are located close to aneye of a user, which presents additional challenges.

SUMMARY

Accordingly, there is a need for improved head-mounted displays.Electro-optic elements, such as beam steering devices, are used toenhance the user's virtual-reality and/or augmented reality experience.However, electro-optic elements often suffer from chromatic dispersion,which includes dispersion of light of different wavelengths intodifferent directions. This generates optical artifacts and reduces theefficiency of the displays.

The above deficiencies and other problems associated with electro-opticelements are reduced or eliminated by the disclosed methods and devices.In some embodiments, the device is a head-mounted display device. Insome embodiments, the device is portable.

In accordance with some embodiments, a method includes sequentiallytransmitting, through a beam steering device, light of a first color andlight of a second color that is distinct from the first color. Themethod also includes applying a first voltage to the beam steeringdevice for transmission of the light of the first color through the beamsteering device; and applying a second voltage to the beam steeringdevice for transmission of the light of the second color through thebeam steering device.

In accordance with some embodiments, a display device includes a beamsteering device; a voltage source; and one or more processors, whereinthe one or more processors are configured to, for sequentialtransmission of light of a first color and light of a second color thatis distinct from the first color: initiate, using the voltage source,application of a first voltage to the beam steering device fortransmission of the light of the first color through the beam steeringdevice; and initiate, using the voltage source, application of a secondvoltage to the beam steering device for transmission of the light of thesecond color through the beam steering device.

Thus, the disclosed embodiments provide compact and light displaydevices with increased efficiency, effectiveness, and user satisfactionwith such devices.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described embodiments,reference should be made to the Description of Embodiments below, inconjunction with the following drawings in which like reference numeralsrefer to corresponding parts throughout the figures.

FIG. 1 is a perspective view of a display device in accordance with someembodiments.

FIG. 2 is a block diagram of a system including a display device inaccordance with some embodiments.

FIG. 3A is an isometric view of an adjustable electronic display elementof a display device in accordance with some embodiments.

FIG. 3B is a partial cross-sectional view of the adjustable electronicdevice in accordance with some embodiments.

FIG. 3C is a perspective view of a tile in accordance with someembodiments.

FIG. 3D is a perspective view of a portion of the adjustable electronicdisplay element in accordance with some embodiments.

FIGS. 3E-3G are schematic diagrams illustrating an exemplary operationof tiles in accordance with some embodiments.

FIGS. 3H and 3I are schematic diagrams illustrating exemplary operationsof activating a subset of tiles in accordance with some embodiments.

FIGS. 4A and 4B are schematic diagrams illustrating back reflection oflight entering an eye in accordance with some embodiments.

FIG. 4C is a graph representing intensity of light reflected by an eyein accordance with some embodiments.

FIGS. 4D-4F are schematic diagrams illustrating methods of determining alocation of a pupil in accordance with some embodiments.

FIG. 4G is a perspective view of a portion of a two-dimensional array oftiles in accordance with some embodiments.

FIG. 4H is a schematic diagram of a display device in accordance withsome embodiments.

FIG. 4I is a schematic diagram of a display device in accordance withsome embodiments.

FIG. 4J is a timing diagram illustrating an operation of an eye trackerin accordance with some embodiments.

FIG. 5 is a flow diagram illustrating a method of activating atwo-dimensional array of tiles based on a location of a pupil of an eyein accordance with some embodiments.

FIGS. 6A and 6B are partial cross-sectional views of an electro-opticelement in accordance with some embodiments.

FIGS. 6C and 6D are plan views of an electro-optic element in accordancewith some embodiments.

FIG. 6E is a schematic diagram illustrating an exemplary operation oftiles in accordance with some embodiments.

FIG. 6F is a schematic diagram illustrating a structure of a liquidcrystal grating in accordance with some embodiments.

FIGS. 6G-6I are schematic diagrams illustrating orientations of nematicliquid crystals in accordance with some embodiments.

FIG. 6J is a schematic diagram illustrating chromatic dispersion in abeam steering device in accordance with some embodiments.

FIGS. 6K-6M are schematic diagrams illustrating sequential adjustment ofdiffraction by a beam steering device in accordance with someembodiments.

FIG. 7 is a flow diagram illustrating a method of directing light from atwo-dimensional array of pixels with an electro-optic element inaccordance with some embodiments.

FIG. 8A is a graph illustrating a perceived resolution for a respectiveregion of a retina in accordance with some embodiments.

FIG. 8B illustrates a non-transformed image, a transformed image, and aprojected image in accordance with some embodiments.

FIG. 8C is a schematic diagram illustrating an exemplary operation oftiles in accordance with some embodiments.

FIG. 9 is a flow diagram illustrating a method of projecting respectiveportions of an image with different resolutions in accordance with someembodiments.

FIGS. 10A and 10B are schematic diagrams illustrating an exemplaryoperation of a tile in accordance with some embodiments.

FIG. 10C is a schematic diagram illustrating a distance model inaccordance with some embodiments.

FIG. 11 is a flow diagram illustrating a method of projecting light witha focal length selected based on proximity of an object in a distancemodel in accordance with some embodiments.

These figures are not drawn to scale unless indicated otherwise.

DETAILED DESCRIPTION

Conventional head-mounted displays are larger and heavier than typicaleyeglasses, because conventional head-mounted displays often include acomplex set of optics that can be bulky and heavy. It is not easy forusers to get used to wearing such large and heavy head-mounted displays.

The disclosed embodiments, by utilizing a combination of a pixel arrayand a microlens (called herein a “tile”), provide display devices(including those that can be head-mounted) that are compact and light.In addition, display devices with an array of tiles can provide a largefield of view, thereby improving user experience with the displaydevices.

Reference will now be made to embodiments, examples of which areillustrated in the accompanying drawings. In the following description,numerous specific details are set forth in order to provide anunderstanding of the various described embodiments. However, it will beapparent to one of ordinary skill in the art that the various describedembodiments may be practiced without these specific details. In otherinstances, well-known methods, procedures, components, circuits, andnetworks have not been described in detail so as not to unnecessarilyobscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc.are, in some instances, used herein to describe various elements, theseelements should not be limited by these terms. These terms are used onlyto distinguish one element from another. For example, a first tile couldbe termed a second tile, and, similarly, a second tile could be termed afirst tile, without departing from the scope of the various describedembodiments. The first tile and the second tile are both tiles, but theyare not the same tile.

The terminology used in the description of the various describedembodiments herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription of the various described embodiments and the appendedclaims, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. The term “exemplary” is used herein in the senseof “serving as an example, instance, or illustration” and not in thesense of “representing the best of its kind.”

FIG. 1 illustrates display device 100 in accordance with someembodiments. In some embodiments, display device 100 is configured to beworn on a head of a user (e.g., by having the form of spectacles oreyeglasses, as shown in FIG. 1) or to be included as part of a helmetthat is to be worn by the user. When display device 100 is configured tobe worn on a head of a user or to be included as part of a helmet,display device 100 is called a head-mounted display. Alternatively,display device 100 is configured for placement in proximity of an eye oreyes of the user at a fixed location, without being head-mounted (e.g.,display device 100 is mounted in a vehicle, such as a car or anairplane, for placement in front of an eye or eyes of the user).

In some embodiments, display device 100 includes one or more componentsdescribed below with respect to FIG. 2. In some embodiments, displaydevice 100 includes additional components not shown in FIG. 2.

FIG. 2 is a block diagram of system 200 in accordance with someembodiments. The system 200 shown in FIG. 2 includes display device 205(which corresponds to display device 100 shown in FIG. 1), imagingdevice 235, and input interface 240 that are each coupled to console210. While FIG. 2 shows an example of system 200 including one displaydevice 205, imaging device 235, and input interface 240, in otherembodiments, any number of these components may be included in system200. For example, there may be multiple display devices 205 each havingassociated input interface 240 and being monitored by one or moreimaging devices 235, with each display device 205, input interface 240,and imaging devices 235 communicating with console 210. In alternativeconfigurations, different and/or additional components may be includedin system 200. For example, in some embodiments, console 210 isconnected via a network (e.g., the Internet) to system 200 or isself-contained as part of display device 205 (e.g., physically locatedinside display device 205). In some embodiments, display device 205 isused to create mixed reality by adding in a view of the realsurroundings. Thus, display device 205 and system 200 described here candeliver virtual reality, mixed reality, and augmented reality.

In some embodiments, as shown in FIG. 1, display device 205 is ahead-mounted display that presents media to a user. Examples of mediapresented by display device 205 include one or more images, video,audio, or some combination thereof. In some embodiments, audio ispresented via an external device (e.g., speakers and/or headphones) thatreceives audio information from display device 205, console 210, orboth, and presents audio data based on the audio information. In someembodiments, display device 205 immerses a user in a virtualenvironment.

In some embodiments, display device 205 also acts as an augmentedreality (AR) headset. In these embodiments, display device 205 augmentsviews of a physical, real-world environment with computer-generatedelements (e.g., images, video, sound, etc.). Moreover, in someembodiments, display device 205 is able to cycle between different typesof operation. Thus, display device 205 operate as a virtual reality (VR)device, an AR device, as glasses or some combination thereof (e.g.,glasses with no optical correction, glasses optically corrected for theuser, sunglasses, or some combination thereof) based on instructionsfrom application engine 255.

Display device 205 includes electronic display 215, one or moreprocessors 216, eye tracking module 217, adjustment module 218, one ormore locators 220, one or more position sensors 225, one or moreposition cameras 222, memory 228, inertial measurement unit (IMU) 230,or a subset or superset thereof (e.g., display device 205 withelectronic display 215, one or more processors 216, and memory 228,without any other listed components). Some embodiments of display device205 have different modules than those described here. Similarly, thefunctions can be distributed among the modules in a different mannerthan is described here.

One or more processors 216 (e.g., processing units or cores) executeinstructions stored in memory 228. Memory 228 includes high-speed randomaccess memory, such as DRAM, SRAM, DDR RAM or other random access solidstate memory devices; and may include non-volatile memory, such as oneor more magnetic disk storage devices, optical disk storage devices,flash memory devices, or other non-volatile solid state storage devices.Memory 228, or alternately the non-volatile memory device(s) withinmemory 228, includes a non-transitory computer readable storage medium.In some embodiments, memory 228 or the computer readable storage mediumof memory 228 stores the following programs, modules and datastructures, or a subset or superset thereof:

-   -   instructions for activating at least a subset of a        two-dimensional array of tiles for outputting, from at least the        subset of the two-dimensional array of tiles, a collective        pattern of light that is directed to a pupil of an eye of a        user;    -   instructions for, prior to activating at least the subset of the        two-dimensional array of tiles, selecting the subset of the        two-dimensional array of tiles for activation;    -   instructions for directing the light from each pixel that        outputs light to a pupil of an eye of a user; and    -   instructions for activating at least the subset of the        two-dimensional array of tiles include instructions for        activating less than all of the tiles of the two-dimensional        array of tiles.

Electronic display 215 displays images to the user in accordance withdata received from console 210 and/or processor(s) 216. In variousembodiments, electronic display 215 may comprise a single adjustableelectronic display element or multiple adjustable electronic displayselements (e.g., a display for each eye of a user). As discussed indetail below with regard to FIGS. 3A-3I, an adjustable electronicdisplay element is comprised of a display element, one or moreintegrated microlens arrays, or some combination thereof. The adjustableelectronic display element may be flat, cylindrically curved, or havesome other shape.

In some embodiments, the display element includes an array of lightemission devices and a corresponding array of emission intensity array.An emission intensity array is an array of electro-optic pixels,opto-electronic pixels, some other array of devices that dynamicallyadjust the amount of light transmitted by each device, or somecombination thereof. These pixels are placed behind an array ofmicrolenses, and are arranged in groups. Each group of pixels outputslight that is directed by the microlens in front of it to a differentplace on the retina where light from these groups of pixels are thenseamlessly “tiled” to appear as one continuous image. In someembodiments, computer graphics, computational imaging and othertechniques are used to pre-distort the image information (e.g.,correcting for the brightness variations) sent to the pixel groups sothat through the distortions of the system from optics, electronics,electro-optics, and mechanicals, a smooth seamless image appears on theback of the retina, as described below with respect to FIGS. 4A and 4B.In some embodiments, the emission intensity array is an array of liquidcrystal based pixels in an LCD (a Liquid Crystal Display). Examples ofthe light emission devices include: an organic light emitting diode, anactive-matrix organic light-emitting diode, a light emitting diode, sometype of device capable of being placed in a flexible display, or somecombination thereof. The light emission devices include devices that arecapable of generating visible light (e.g., red, green, blue, etc.) usedfor image generation. The emission intensity array is configured toselectively attenuate individual light emission devices, groups of lightemission devices, or some combination thereof. Alternatively, when thelight emission devices are configured to selectively attenuateindividual emission devices and/or groups of light emission devices, thedisplay element includes an array of such light emission devices withouta separate emission intensity array.

The microlens arrays are arrays of lenslets that direct light from thearrays of light emission devices (optionally through the emissionintensity arrays) to locations within each eyebox and ultimately to theback of the user's retina(s). An eyebox is a region that is occupied byan eye of a user located proximity to display device 205 (e.g., a userwearing display device 205) for viewing images from display device 205.In some cases, the eyebox is represented as a 10 mm×10 mm square (see,e.g., FIG. 3D). In some embodiments, a lenslet is a conventional passivelens (e.g., glass lens, plastic lens, etc.) or an active lens (e.g.,liquid crystal lens, liquid lens, etc.). In some embodiments, displaydevice 205 dynamically adjusts the curvature and/or refractive abilityof active lenslets to direct light to specific locations within eacheyebox (e.g., location of pupil). In some embodiments, one or more ofthe microlens arrays include one or more coatings, such asanti-reflective coatings.

In some embodiments, the display element includes an infrared (IR)detector array that detects IR light that is retro-reflected from theretinas of a viewing user, from the surface of the corneas, lenses ofthe eyes, or some combination thereof. The IR detector array includes anIR sensor or a plurality of IR sensors that each correspond to adifferent position of a pupil of the viewing user's eye. In alternateembodiments, other eye tracking systems may also be employed.

Eye tracking module 217 determines locations of each pupil of a user'seyes. In some embodiments, eye tracking module 217 instructs electronicdisplay 215 to illuminate the eyebox with IR light (e.g., via IRemission devices in the display element).

A portion of the emitted IR light will pass through the viewing user'spupil and be retro-reflected from the retina toward the IR detectorarray, which is used for determining the location of the pupil.Alternatively, the reflection off of the surfaces of the eye is used toalso determine location of the pupil. The IR detector array scans forretro-reflection and identifies which IR emission devices are activewhen retro-reflection is detected. Eye tracking module 217 may use atracking lookup table and the identified IR emission devices todetermine the pupil locations for each eye. The tracking lookup tablemaps received signals on the IR detector array to locations(corresponding to pupil locations) in each eyebox. In some embodiments,the tracking lookup table is generated via a calibration procedure(e.g., user looks at various known reference points in an image and eyetracking module 217 maps the locations of the user's pupil while lookingat the reference points to corresponding signals received on the IRtracking array). As mentioned above, in some embodiments, system 200 mayuse other eye tracking systems than the embedded IR one described above.

Adjustment module 218 generates an image frame based on the determinedlocations of the pupils. This sends a discrete image to the display thatwill tile subimages together thus a coherent stitched image will appearon the back of the retina. A small portion of each image is projectedthrough each lenslet in the lenslet array. Adjustment module 218 adjustsan output (i.e. the generated image frame) of electronic display 215based on the detected locations of the pupils. Adjustment module 218instructs portions of electronic display 215 to pass image light to thedetermined locations of the pupils. In some embodiments, adjustmentmodule 218 also instructs the electronic display to not pass image lightto positions other than the determined locations of the pupils.Adjustment module 218 may, for example, block and/or stop light emissiondevices whose image light falls outside of the determined pupillocations, allow other light emission devices to emit image light thatfalls within the determined pupil locations, translate and/or rotate oneor more display elements, dynamically adjust curvature and/or refractivepower of one or more active lenslets in the microlens arrays, or somecombination thereof.

In some embodiments, adjustment module 218 is configured to instruct thedisplay elements to not use every pixel (e.g., one or more lightemission devices), such that black spaces aperture the diverging lightto abut the image together from the retinal perspective. In addition, insome embodiments, gaps are created between the pixel groups or “tiles”to match divergence of the light source array and the magnification ofthe group of pixels as it transverses through the optical system andfully fills the lenslet. In some embodiments, adjustment module 218determines, for a given position of an eye, which pixels are turned onand which pixels are turned off, with the resulting image beingseamlessly tiled on the eye's retina.

Optional locators 220 are objects located in specific positions ondisplay device 205 relative to one another and relative to a specificreference point on display device 205. A locator 220 may be a lightemitting diode (LED), a corner cube reflector, a reflective marker, atype of light source that contrasts with an environment in which displaydevice 205 operates, or some combination thereof. In embodiments wherelocators 220 are active (i.e., an LED or other type of light emittingdevice), locators 220 may emit light in the visible band (e.g., about400 nm to 750 nm), in the infrared band (e.g., about 750 nm to 1 mm), inthe ultraviolet band (about 100 nm to 400 nm), some other portion of theelectromagnetic spectrum, or some combination thereof.

In some embodiments, locators 220 are located beneath an outer surfaceof display device 205, which is transparent to the wavelengths of lightemitted or reflected by locators 220 or is thin enough to notsubstantially attenuate the wavelengths of light emitted or reflected bylocators 220. Additionally, in some embodiments, the outer surface orother portions of display device 205 are opaque in the visible band ofwavelengths of light. Thus, locators 220 may emit light in the IR bandunder an outer surface that is transparent in the IR band but opaque inthe visible band.

IMU 230 is an electronic device that generates calibration data based onmeasurement signals received from one or more position sensors 225.Position sensor 225 generates one or more measurement signals inresponse to motion of display device 205. Examples of position sensors225 include: one or more accelerometers, one or more gyroscopes, one ormore magnetometers, another suitable type of sensor that detects motion,a type of sensor used for error correction of IMU 230, or somecombination thereof. Position sensors 225 may be located external to IMU230, internal to IMU 230, or some combination thereof.

Based on the one or more measurement signals from one or more positionsensors 225, IMU 230 generates first calibration data indicating anestimated position of display device 205 relative to an initial positionof display device 205. For example, position sensors 225 includemultiple accelerometers to measure translational motion (forward/back,up/down, left/right) and multiple gyroscopes to measure rotationalmotion (e.g., pitch, yaw, roll). In some embodiments, IMU 230 rapidlysamples the measurement signals and calculates the estimated position ofdisplay device 205 from the sampled data. For example, IMU 230integrates the measurement signals received from the accelerometers overtime to estimate a velocity vector and integrates the velocity vectorover time to determine an estimated position of a reference point ondisplay device 205. Alternatively, IMU 230 provides the sampledmeasurement signals to console 210, which determines the firstcalibration data. The reference point is a point that may be used todescribe the position of display device 205. While the reference pointmay generally be defined as a point in space; however, in practice thereference point is defined as a point within display device 205 (e.g., acenter of IMU 230).

In some embodiments, IMU 230 receives one or more calibration parametersfrom console 210. As further discussed below, the one or morecalibration parameters are used to maintain tracking of display device205. Based on a received calibration parameter, IMU 230 may adjust oneor more IMU parameters (e.g., sample rate). In some embodiments, certaincalibration parameters cause IMU 230 to update an initial position ofthe reference point so it corresponds to a next calibrated position ofthe reference point. Updating the initial position of the referencepoint as the next calibrated position of the reference point helpsreduce accumulated error associated with the determined estimatedposition. The accumulated error, also referred to as drift error, causesthe estimated position of the reference point to “drift” away from theactual position of the reference point over time.

Imaging device 235 generates calibration data in accordance withcalibration parameters received from console 210. Calibration dataincludes one or more images showing observed positions of locators 220that are detectable by imaging device 235. In some embodiments, imagingdevice 235 includes one or more still cameras, one or more videocameras, any other device capable of capturing images including one ormore locators 220, or some combination thereof. Additionally, imagingdevice 235 may include one or more filters (e.g., used to increasesignal to noise ratio). Imaging device 235 is configured to optionallydetect light emitted or reflected from locators 220 in a field of viewof imaging device 235. In embodiments where locators 220 include passiveelements (e.g., a retroreflector), imaging device 235 may include alight source that illuminates some or all of locators 220, whichretro-reflect the light towards the light source in imaging device 235.Second calibration data is communicated from imaging device 235 toconsole 210, and imaging device 235 receives one or more calibrationparameters from console 210 to adjust one or more imaging parameters(e.g., focal length, focus, frame rate, ISO, sensor temperature, shutterspeed, aperture, etc.).

Input interface 240 is a device that allows a user to send actionrequests to console 210. An action request is a request to perform aparticular action. For example, an action request may be to start or endan application or to perform a particular action within the application.Input interface 240 may include one or more input devices. Example inputdevices include: a keyboard, a mouse, a game controller, data from brainsignals, data from other parts of the human body, or any other suitabledevice for receiving action requests and communicating the receivedaction requests to console 210. An action request received by inputinterface 240 is communicated to console 210, which performs an actioncorresponding to the action request. In some embodiments, inputinterface 240 may provide haptic feedback to the user in accordance withinstructions received from console 210. For example, haptic feedback isprovided when an action request is received, or console 210 communicatesinstructions to input interface 240 causing input interface 240 togenerate haptic feedback when console 210 performs an action.

Console 210 provides media to display device 205 for presentation to theuser in accordance with information received from one or more of:imaging device 235, display device 205, and input interface 240. In theexample shown in FIG. 2, console 210 includes application store 245,tracking module 250, and application engine 255. Some embodiments ofconsole 210 have different modules than those described in conjunctionwith FIG. 2. Similarly, the functions further described below may bedistributed among components of console 210 in a different manner thanis described here.

When application store 245 is included in console 210, application store245 stores one or more applications for execution by console 210. Anapplication is a group of instructions, that when executed by aprocessor, is used for generating content for presentation to the user.Content generated by the processor based on an application may be inresponse to inputs received from the user via movement of display device205 or input interface 240. Examples of applications include: gamingapplications, conferencing applications, video playback application, orother suitable applications.

When tracking module 250 is included in console 210, tracking module 250calibrates system 200 using one or more calibration parameters and mayadjust one or more calibration parameters to reduce error indetermination of the position of display device 205. For example,tracking module 250 adjusts the focus of imaging device 235 to obtain amore accurate position for observed locators on display device 205.Moreover, calibration performed by tracking module 250 also accounts forinformation received from IMU 230. Additionally, if tracking of displaydevice 205 is lost (e.g., imaging device 235 loses line of sight of atleast a threshold number of locators 220), tracking module 250re-calibrates some or all of system 200.

In some embodiments, tracking module 250 tracks movements of displaydevice 205 using second calibration data from imaging device 235. Forexample, tracking module 250 determines positions of a reference pointof display device 205 using observed locators from the secondcalibration data and a model of display device 205. In some embodiments,tracking module 250 also determines positions of a reference point ofdisplay device 205 using position information from the first calibrationdata. Additionally, in some embodiments, tracking module 250 may useportions of the first calibration data, the second calibration data, orsome combination thereof, to predict a future location of display device205. Tracking module 250 provides the estimated or predicted futureposition of display device 205 to application engine 255.

Application engine 255 executes applications within system 200 andreceives position information, acceleration information, velocityinformation, predicted future positions, or some combination thereof ofdisplay device 205 from tracking module 250. Based on the receivedinformation, application engine 255 determines content to provide todisplay device 205 for presentation to the user. For example, if thereceived information indicates that the user has looked to the left,application engine 255 generates content for display device 205 thatmirrors the user's movement in a virtual environment. Additionally,application engine 255 performs an action within an applicationexecuting on console 210 in response to an action request received frominput interface 240 and provides feedback to the user that the actionwas performed. The provided feedback may be visual or audible feedbackvia display device 205 or haptic feedback via input interface 240.

FIG. 3A is an isometric view of an adjustable electronic display element300 of display device 205, in accordance with some embodiments. In someother embodiments, adjustable electronic display element 300 is part ofsome other electronic display (e.g., digital microscope, etc.). In someembodiments, adjustable electronic display element 300 includes lightemission device array 305, emission intensity array 310, microlens array315, and IR detector array 320. In some other embodiments, adjustableelectronic display element 300 includes a subset or superset of lightemission device array 305, emission intensity array 310, microlens array315, and IR detector array 320 (e.g., adjustable electronic displayelement 300 includes an adjustable light emission device array thatincludes individually adjustable pixels and microlens array 315, withouta separate emission intensity array).

Light emission device array 305 emits image light and optional IR lighttoward the viewing user. Light emission device array 305 may be, e.g.,an array of LEDs, an array of microLEDs, an array of OLEDs, or somecombination thereof. Light emission device array 305 includes lightemission devices that emit light in the visible light (and optionallyincludes devices that emit light in the IR).

Emission intensity array 310 is configured to selectively attenuatelight emitted from light emission array 305. In some embodiments,emission intensity array 310 is composed of a plurality of liquidcrystal cells or pixels, groups of light emission devices, or somecombination thereof. Each of the liquid crystal cells is, or in someembodiments, groups of liquid crystal cells are, addressable to havespecific levels of attenuation. For example, at a given time, some ofthe liquid crystal cells may be set to no attenuation, while otherliquid crystal cells may be set to maximum attenuation. In this manneremission intensity array 310 is able to control what portion of theimage light emitted from light emission device array 305 is passed tothe microlens array 315. In some embodiments, display device 205 usesemission intensity array 310 to facilitate providing image light to alocation of pupil 330 of eye 325 of a user, and minimize the amount ofimage light provided to other areas in the eyebox.

Microlens array 315 receives the modified image light (e.g., attenuatedlight) from emission intensity array 310, and directs the modified imagelight to a location of pupil 330. Microlens array 315 includes aplurality of lenslets. In some embodiments, microlens array 315 includesone or more diffractive optics. A lenslet may be a conventional passivelens (e.g., glass lens, plastic lens, etc.) or an active lens. An activelens is a lens whose lens curvature and/or refractive ability may bedynamically controlled (e.g., via a change in applied voltage). Anactive lens may be a liquid crystal lens, a liquid lens (e.g., usingelectro-wetting), or some other lens whose curvature and/or refractiveability may be dynamically controlled, or some combination thereof.Accordingly, in some embodiments, system 200 may dynamically adjust thecurvature and/or refractive ability of active lenslets to direct lightreceived from emission intensity array 310 to pupil 330.

Optional IR detector array 320 detects IR light that has beenretro-reflected from the retina of eye 325, a cornea of eye 325, acrystalline lens of eye 325, or some combination thereof. IR detectorarray 320 includes either a single IR sensor or a plurality of IRsensitive detectors (e.g., photodiodes). While IR detector array 320 inFIG. 3A is shown separate from light emission device array 305, in someembodiments, IR detector array 320 may be integrated into light emissiondevice array 305.

In some embodiments, light emission device array 305 and emissionintensity array 310 make up a display element. Alternatively, thedisplay element includes light emission device array 305 (e.g., whenlight emission device array 305 includes individually adjustable pixels)without emission intensity array 310. In some embodiments, the displayelement additionally includes IR array 320. In some embodiments, inresponse to a determined location of pupil 335, the display elementadjusts the emitted image light such that the light output by thedisplay element is refracted by microlens array 315 toward the locationof pupil 335, and not toward other locations in the eyebox.

FIG. 3B is a partial cross-sectional view of adjustable electronicdevice 340 in accordance with some embodiments.

Adjustable electronic device 340 includes a two-dimensional array oftiles 360 (e.g., 10-by-10 array of tiles 360, as shown in FIG. 3B). Insome cases, each tile has a shape of a 1-mm-by-1-mm square, althoughtiles of different sizes and/or shapes can be used. In some embodiments,the two-dimensional array of tiles 360 is arranged on a flat surface. Insome other embodiments, the two-dimensional array of tiles 360 isarranged on a curved surface or a surface of any other shape. AlthoughFIG. 3B shows a square array of tiles 360, in some other embodiments,the two-dimensional array of tiles 360 may have a rectangular shape, orany other shape (e.g., a rasterized circle or a rasterized ellipse). Inaddition, a different number of tiles 360 may be used depending on thedesired performance of the display device (e.g., a field of view).

As explained above, tile 360 includes a lens. In some embodiments,lenses for the two-dimensional array of tiles are provided in a form ofa microlens array (e.g., microlens array 315 in FIG. 3A). In FIG. 3B, aportion of the microlens array is not shown (e.g., an upper-left portionof the microlens array indicated by the line XX′) to illustrate groupsof pixels located behind it.

FIG. 3B also illustrates that each tile 360 includes a two-dimensionalarray 344 of pixels 346 (e.g., 10-by-10 array of pixels). In some otherembodiments, the tiles 360 may include different numbers of pixels(e.g., 40-by-40 pixels).

In some embodiments, the two-dimensional array 344 of pixels 346 doesnot encompass the entire surface of tile 360, as shown in FIG. 3B. Insuch embodiments, a portion of tile 360 (e.g., an area along a peripheryof tile 360) not covered by the pixels 346 includes electronic circuitsfor operating pixels 346 on tile 360 (e.g., adjusting individual pixels346 and/or subpixels to turn on or off).

In FIG. 3B, each pixel 346 includes a plurality of subpixels (e.g.,subpixel 348, 350, 352, and 354), where each subpixel corresponds to arespective color. For example, each pixel may include three subpixels,each subpixel outputting light of one of red, green, and blue colors. Inanother example, each pixel may include four subpixels, each subpixeloutputting to one of red, green, blue, and yellow colors (e.g., subpixel348 outputs red light, subpixel 350 outputs green light, subpixel 352outputs blue light, and subpixel 354 outputs yellow light). In somecases, this is enabled by placing different color filters in front ofthe subpixels. In some embodiments, the subpixels in each pixel have thesame size (e.g., the red subpixel, the green subpixel, and the bluesubpixel have the same size), while in some other embodiments, thesubpixels have different sizes (e.g., to compensate for differentintensities of light of different colors).

In some embodiments, each tile 360 in the two-dimensional array of tileshas a same configuration. For example, each tile may have the same shapeand size, and include a same number of pixels. In some embodiments,tiles in the two-dimensional array of tiles have differentconfigurations (e.g., tiles having one of two different configurationsare alternated).

In some embodiments, each tile includes a two-dimensional array oflenses. For example, the tile may have the same number of pixels andlenses so that each pixel is coupled with a respective lens. In someembodiments, each single lens is integrated with a respective pixel(e.g., each single lens is placed on, or included as part of, therespective pixel).

FIG. 3C is a perspective view of tile 360 in accordance with someembodiments. As explained above, tile 360 includes two-dimensional array344 of pixels 346 and lens 342, which may be a lenslet of a microlensarray (e.g., microlens array 315 in FIG. 3A). In some embodiments, tile360 includes a single lens. In some other embodiments, tile 360 includestwo or more lenses along the optical axis (e.g., second lens 362 islocated between pixels 346 and lens 342).

FIG. 3D is a perspective view of a portion of the adjustable electronicdisplay element in accordance with some embodiments. The perspectiveview 380 includes a portion of the electronic display element and eyebox386. For example, the portion includes tiles 382A, 382B, and 382C, andlenslets 384A, 384B, and 384C in those tiles. In some cases, eyebox 386has a dimension of 10 mm×10 mm, although eyeboxes of different sizes canbe used. When pupil 330 is at position 388, the image is rendered forthis portion of eyebox 386, and light is directed from different tiles,including tiles 382A, 382B, and 382C to form an image on a retina of theeye.

FIGS. 3E-3G are schematic diagrams illustrating exemplary operations oftiles in accordance with some embodiments.

FIG. 3E illustrates three tiles (e.g., a first tile with group 344A ofpixels and lens 342A, a second tile with group 344B of pixels and lens342B, and a third tile with group 344C of pixels and lens 342C). Pixels344 in each tile render a respective pattern of light, which is directedby lens 342 in the tile to pupil 330 of eye 325. The respective patternof light from group 344A of pixels forms an image on a first portion332A of a retina of eye 325, the respective pattern of light from group344B of pixels forms an image on a second portion 332B of the retina ofeye 325, and the respective pattern of light from group 344C of pixelsforms an image on a third portion 332C of the retina of eye 325, asshown in FIG. 3G. Thus, the respective patterns of light from pixelgroups 344A, 344B, and 344C form a collective pattern of light, which isseamlessly projected onto the retina of eye 325, which is perceived bythe eye as a single image. In some embodiments, as shown in FIG. 3F, oneor more lenses (e.g., lens 342A and 342C) are tilted to better directlight toward pupil 330 of eye 325.

It should be noted that display devices described herein are distinctfrom what is known as light field displays. Light field displays projectpartially overlapping series of images. However, light field displayshave a limited field of view. In comparison, the disclosed displaydevices provide a large field of view that has not been possible withlight field displays, and therefore, can be used for a wider range ofapplications.

FIGS. 3H and 3I are schematic diagrams illustrating exemplary operationsof activating a subset of tiles in accordance with some embodiments.FIG. 3H illustrates an array of 5-by-5 tiles, where five tiles out ofthe 25 tiles are shown in the side view (e.g., tiles with pixel groups344D, 344A, 344B, 344C, and 344E and corresponding lenses 342D, 342A,342B, 342C, and 342E). As explained above with respect to FIGS. 3E-3G,the respective pattern of light from group 344A of pixels forms an imageon a first portion 332A of a retina of eye 325, the respective patternof light from group 344B of pixels forms an image on a second portion332B of the retina of eye 325, and the respective pattern of light fromgroup 344C of pixels forms an image on a third portion 332C of theretina of eye 325. However, group 344D of pixels and group 344E ofpixels are not activated. In some embodiments, group 344D of pixels andgroup 344E of pixels are not activated, because light output from group344D of pixels and group 344E of pixels cannot be directed to pupil 330of eye 325 (or because the light output from group 344D of pixels andgroup 344E of pixels cannot form an image on the retina of eye 325). Insome embodiments, group 344D of pixels and group 344E of pixels are notactivated, because the light output from group 344D of pixels and group344E of pixels are not necessary for forming an image on the retina ofeye 325. In some embodiments, group 344D of pixels and group 344E ofpixels are not activated, because light output from group 344D of pixelsand group 344E of pixels cannot be directed to pupil 330 of eye 325 (orbecause the light output from group 344D of pixels and group 344E ofpixels cannot form an image on the retina of eye 325).

In some embodiments, a group of pixels that is not activated does notoutput light toward the pupil of the eye. In some embodiments, a groupof pixels that is not activated does not output light at all. In someembodiments, a group of pixels that is not activated is turned off orremains in a power savings mode, thereby reducing consumption of energy.

FIG. 3H also illustrates that out of the twenty-five tiles, ninecontiguous tiles (including tiles 360A, 360B, and 360C) are activated(which are shaded in FIG. 3H) and the remaining sixteen tiles (includingtiles 360D and 360E) are not activated (which are not shaded in FIG.3H).

In some embodiments, as shown in FIG. 3I, one or more lenses (e.g., lens342A, 342C, 342D, and 342E) are tilted to better direct light towardpupil 330 of eye 325.

FIGS. 4A and 4B are schematic diagrams illustrating back reflection oflight entering eye 402 in accordance with some embodiments.

In some embodiments, a retina of an eye reflects infrared light (e.g., adeer in the headlights). In particular, a central region of the retinahas a higher reflectivity than a non-central region of the retina. Forexample, in FIG. 4A, ray 404 of light hitting a central region of theretina is reflected better than rays 406 and 408 of light hittingnon-central regions of the retina. Thus, by measuring the intensity ofthe reflected light, an angle (or a gaze) of eye 402 can be determined.

In FIG. 4B, rays 412, 414, and 46 of light entering eye 402 arereflected better by the retina of eye 402 than rays 410 and 418 oflight, which are reflected by a sclera of eye 402. In addition, ray 414of light that is reflected by a central region of eye 402 is reflectedbetter than rays 412 and 416 of light that are reflected by non-centralregions of eye 402.

FIG. 4C is a graph representing intensity of light reflected by an eyein accordance with some embodiments. As shown in FIG. 4C, lightreflected by a central region of an eye has a higher intensity than anon-central region of the eye. Thus, in some embodiments, a location ofthe eye (e.g., a location of a pupil of the eye) is determined from aprofile of the intensity of light reflected by the eye (e.g., a locationwith the highest intensity of reflected light corresponds to a positionof a center of the eye).

FIGS. 4D-4F are schematic diagrams illustrating methods of determining alocation of a pupil in accordance with some embodiments.

In FIG. 4D, emitters 422 and sensors 420 are used to determine alocation of a pupil of eye 402. In some embodiments, as shown in FIG.4D, one emitter 422 is paired with one sensor 420 to determine thelocation of the pupil of eye 402. For example, emitter 422 is configuredto emit non-visible light (e.g., infrared light). Sensor 420 isconfigured to receive reflected non-visible light (e.g., non-visiblelight reflected by eye 402). From a profile of the intensity of lightreceived by sensors 420, an angle (or a gaze) of eye 402 is determined.In some embodiments, when light from emitters 422 is directed toward apupil of eye 402, sensor 420 with a highest intensity of the reflectedlight is determined to correspond to the angle (or the gaze) of eye 402.In some embodiments, the device includes a single emitter. In someembodiments, the device includes a single sensor. In some embodiments,sensors 420 are arranged in an array (e.g., the device includes an arrayof sensors). In some embodiments, emitters 422 are arranged in an array(e.g., the device includes an array of emitters).

In some embodiments, as shown in FIG. 4D, the display device includeslens 424 and/or lens 426. Lens 426 is configured to direct light fromemitter 422 toward eye 402. Lens 424 is configured to direct lightreflected by eye 402 toward sensor 420.

In some embodiments, the display device includes one or more polarizers428 (e.g., a combination of a linear polarizer and a quarter wave plate)to reduce specular reflection of light by a cornea of eye 402.

In FIG. 4E, an array of emitter-sensor pairs is used to determine aposition of eye 402. Lens 426 is configured to direct lightindependently of a location of eye 402 (e.g., forward). In FIG. 4E,light from an array of emitters 422 is directed forward, instead ofbeing directed toward a single location (e.g., a pupil of eye 402) asshown in FIG. 4D. In some embodiments, sensor 420 with a highestintensity of the reflected light is determined to correspond to aposition of eye 402 (or a position of a pupil of eye 402).

FIG. 4F illustrates that, in some embodiments, an intensity of lightreflected from different positions of eye 402 is sequentially measured.For example, at least a portion of the eye is linearly scanned (e.g., ina raster pattern).

FIG. 4G is a perspective view of a portion of a two-dimensional array oftiles 360 in accordance with some embodiments. As shown in FIG. 4G, eachtile 360 in FIG. 4G includes a two-dimensional array of pixels 346formed on a substrate. FIG. 4G also illustrates that each tile 360includes emitter 432 and one or more sensors 430 and 434 formed on thesame substrate. Thus, the two-dimensional array of pixels 346, emitter432, and one or more sensors 430 and 434 are located on a same plane.Although FIG. 4G shows that each tile 360 has one emitter 432, in someembodiments, each tile 360 has multiple emitters (e.g., each tile 360may have as many emitters as a number of pixels in tile 360). In someembodiments, multiple tiles collectively have one emitter (e.g., a groupof two or four tiles has only one emitter).

FIG. 4H is a schematic diagram of a display device in accordance withsome embodiments.

The display device includes sensor panel 440 that includes one or moreemitters (e.g., an array of emitters) and one or more sensors (e.g., anarray of sensors). In some embodiments, the emitters are interspersedwithin the sensors.

In some embodiments, the display device also includes array 442 oflenses configured for directing light from emitters toward eye 402 anddirect light, reflected by eye 402, toward sensors.

The display device includes two-dimensional array 444 of tiles. In someembodiments, two-dimensional array 444 of tiles is transparent toinfrared light. Thus, infrared light emitted by emitters in sensor panel440 passes through two-dimensional array 444 of tiles toward eye 402.Similarly, infrared light, reflected by eye 402, passes throughtwo-dimensional array 444 of tiles toward sensor panel 440.

In some embodiments, the display device also includes array 446 oflenses (or an array of lens assemblies), which are described above. Forbrevity, the detailed description of array 446 of lenses is not repeatedherein.

FIG. 4I is a schematic diagram of a display device in accordance withsome embodiments.

In FIG. 4I, the display device includes electro-optics 448 (or an arrayof electro-optic elements). Electro-optics 448 is configured to adjustfocusing and/or steering of light propagating from and/or toward sensorpanel 440. In some embodiments, electro-optics 448 includes a liquidcrystal layer.

In some embodiments, the two-dimensional array of tiles is integrated insensor panel 440. Thus, the same lens array 442 is used for directinglight from emitters and light from the two-dimensional array of pixels.This reduces, or eliminates, the need for complex processing of imagecollected by the sensors, because the sensors are collocated with thedisplay pixels. Light from a display pixel and light collected by asensor adjacent to the display pixel follow paths, that are proximate toeach other, through a same lens.

FIG. 4J is a timing diagram illustrating an operation of an eye trackerin accordance with some embodiments.

In FIG. 4J, the operation of the eye tracker is illustrated with respectto frames. Each frame corresponds to preselected time duration (e.g., 10ms). A series of operations is performed within a single frame.

In some embodiments, a reset voltage (e.g., a global pixel voltage) isprovided (460) to the pixels, which clears (or resets) liquid crystalsin pixels. Subsequently, an eye tracking operation is performed (462) todetermine a location of a pupil of an eye (and an angle of the eye).Information about the location of the eye (e.g., the location of thepupil of the eye and/or the angle of the eye) is provided (464) to oneor more processors (e.g., processor(s) 216, FIG. 2). In someembodiments, the one or more processors subsequently render one or moreframes for display.

Pixel voltages are applied (466) to the pixels, which initiates placingthe pixels in respective states for displaying a rendered frame. In someembodiments, voltages are applied to activate electro-optic components(e.g., liquid crystal lenses and/or beam steerers). In some embodiments,the display device waits (468) until liquid crystals in respectivepixels settle. Subsequently, the display device turns on a backlight sothat a respective pattern of light is output from a respective tile.

In some embodiments, these steps are repeated for subsequent frames.

Certain embodiments based on these principles are described below.

In accordance with some embodiments, display device 100 includes atwo-dimensional array of tiles (e.g., two-dimensional array of tiles 340in FIG. 3B). Each tile (e.g., tile 360 in FIG. 3C) includes atwo-dimensional array of pixels (e.g., two-dimensional array 340 ofpixels 346 in FIG. 3C). Each pixel is configured to output light so thatthe two-dimensional array of pixels outputs a respective pattern oflight (e.g., two-dimensional array of pixels 344A in FIG. 3G outputs apattern of light that corresponds to a top portion of a triangle, twodimensional array of pixels 344B in FIG. 3G outputs a pattern of lightthat corresponds to a middle portion of the triangle, andtwo-dimensional array of pixels 344C in FIG. 3G outputs a pattern oflight that corresponds to a bottom portion of the triangle). The tilealso includes a lens (e.g., lens 342 in FIG. 3C), of a two-dimensionalarray of lenses, configured to direct at least a portion of therespective pattern of light from the two-dimensional array of pixels toa pupil of an eye of a user. Display device 100 includes one or moresensors for determining a location of the pupil of the eye of the user(e.g., sensor plate 440 in FIG. 4H). In some embodiments, display device100 includes an array of sensors for determining the location of thepupil of the eye of the user.

In some embodiments, display device 100 includes a substrate (e.g.,sensor plate 440). The two-dimensional array of pixels and the one ormore sensors are located on the same substrate. In some embodiments, thearray of sensors is located on the same substrate.

In some embodiments, each tile includes one or more sensors. In someembodiments, each tile includes at least one sensor of the array ofsensors (e.g., each tile 360 includes sensor 430, FIG. 4G). In someembodiments, display device 100 includes only one sensor for determiningthe location of the pupil of the eye of the user.

In some embodiments, display device 100 includes an array of emittersconfigured to emit non-visible light (e.g., an array of emitters 432 inFIG. 4G). Each emitter is coupled with a respective sensor (e.g., eachemitter 432 is coupled with respective sensor 430). In some embodiments,each emitter is coupled with a respective sensor of the array ofsensors. In some embodiments, display device 100 includes only a singleemitter.

In some embodiments, display device 100 includes an array of emitters(e.g., an array of emitters 432 in FIG. 4G) configured to emitnon-visible light (e.g., infrared light). Each emitter is coupled with arespective group of multiple sensors located adjacent to the emitter(e.g., in FIG. 4G, each emitter 432 is coupled with adjacent sensors 430and 434). In some embodiments, each emitter is coupled with a respectivegroup of multiple sensors, of the array of sensors, located adjacent tothe emitter.

In some embodiments, display device 100 includes multiple arrays ofsensors for determining the location of the pupil of the eye of the user(e.g., an array of sensors 430 and a separate array of sensors 434). Arespective array is separate from the rest of the multiple arrays ofsensors. This allows a shorter interval between eye tracking operations.For example, each sensor may have a certain delay in collecting lightreceived by the sensors so that an interval between determiningpositions of a pupil of an eye is 10 ms. By using a first half of thesensors (e.g., sensors 430) concurrently and subsequently using a secondhalf of the sensors (e.g., sensors 434) together, the interval betweendetermining positions of the pupil of the eye is reduced to 5 ms (=10ms/2). When three groups of sensors are used, the interval betweendetermining positions of the pupil of the eye is reduced to 3.3 ms (≈10ms/3).

In some embodiments, display device 100 includes one or more polarizers(e.g., one or more polarizers 428 in FIG. 4D) configured to reduce lightreflected from a cornea of the eye of the user toward the one or moresensors. In some embodiments, display device 100 includes one or morepolarizers (e.g., one or more polarizers 428 in FIG. 4D) configured toreduce light reflected from a cornea of the eye of the user toward thearray of sensors.

In some embodiments, display device 100 includes one or more processors(e.g., processor(s) 216, FIG. 2) coupled with the two-dimensional arrayof tiles and configured to select a subset of the two-dimensional arrayof tiles based on the location of the pupil of the eye of the user andactivate the subset of the two-dimensional array of tiles foroutputting, from at least the subset of the two-dimensional array oftiles, a collective pattern of light that is directed to the pupil ofthe eye of the user. For example, when the position of the pupil of theeye is determined, tiles that are located far from the position of thepupil of the eye are not selected. Because the tiles that are locatedfar from the position of the pupil of the eye are not likely to outputlight that will enter the pupil of the eye of the user, by keeping thetiles that are located far from the position of the pupil of the eyeoff, the display device can save power.

In some embodiments, the one or more processors (e.g., processor(s) 216,FIG. 2) are configured to activate the one or more sensors fordetermining the location of the pupil of the eye of the user betweenactivating the subset of the two-dimensional array of tiles. Forexample, the one or more sensors are activated in frame 2 (FIG. 4J)between determining activating a subset of a two-dimensional array oftiles in frame 1 and activating a subset of the two-dimensional array oftiles in frame 2. In some embodiments, the one or more processors areconfigured to activate the array of sensors for determining the locationof the pupil of the eye of the user between activating the subset of thetwo-dimensional array of tiles.

In some embodiments, the one or more processors (e.g., processor(s) 216,FIG. 2) are configured to concurrently activate less than all of thesensors for determining the location of the pupil of the eye of theuser. In some embodiments, the one or more processors are configured toactivate at least a subset of the array of sensors concurrently fordetermining the location of the pupil of the eye of the user. Forexample, as shown in FIG. 4E, multiple sensors are activatedconcurrently to determine the location of the pupil of the eye of theuser.

In some embodiments, the one or more processors are configured tosequentially activate at least a subset of the array of sensors fordetermining the location of the pupil of the eye of the user. Forexample, as shown in FIG. 4D, multiple sensors are activated todetermine the angle (or the gaze) of eye 402. In some embodiments, themultiple sensor are activated sequentially (e.g., in a raster pattern).In some embodiments, the multiple sensors are activated concurrently.

In some embodiments, the one or more processors are configured tosequentially activate less than all of the sensors for determining anangle of the pupil of the eye of the user. In some embodiments, the oneor more processors are configured to activate at least a subset of thearray of sensors sequentially for determining an angle of the pupil ofthe eye of the user. In some embodiments, the subset of the array ofsensors is selected based on the location of the pupil of the eye of theuser (e.g., the location of the pupil of the eye of the user isdetermined by activating at least a subset of the array of sensorsconcurrently, followed by sequentially activating the subset of thearray of sensors for determining the angle of the pupil of the eye).

In some embodiments, the one or more processors are configured toconcurrently activate at least a subset of the sensors for determiningthe location of the pupil of the eye of the user and subsequentlyactivate sequentially at least a subset of the sensors for determiningan angle of the pupil of the eye of the user. In some embodiments, theone or more processors are configured to concurrently activate at leasta subset of the array of sensors for determining the location of thepupil of the eye of the user and subsequently activate sequentially atleast a subset of the array of sensors for determining an angle of thepupil of the eye of the user.

In some embodiments, the one or more processors are configured to adjustthe location of the pupil of the eye of the user for an interpupilarydistance of the pupil of the eye of the user. For example, when theinterpupilary distance of the pupil of the eye of the user is known(e.g., based on a manual input or a manual adjustment of the displaydevice), the location of the pupil of the eye of the user is estimatedbased on the interpupilary distance of the pupil of the eye of the user.

FIG. 5 is a flow diagram illustrating method 500 of activating atwo-dimensional array of tiles based on a location of a pupil of an eyein accordance with some embodiments. Method 500 is performed at adisplay device (e.g., display device 100 in FIG. 1) comprising atwo-dimensional array of tiles (e.g., FIG. 3B). Each tile includes(e.g., FIG. 3C) a two-dimensional array of pixels (e.g., 344). Eachpixel is configured to output light so that the two-dimensional array ofpixels outputs a respective pattern of light (e.g., FIG. 3G). Each tilealso includes a lens (e.g., 342), of a two-dimensional array of lenses,configured to direct at least a portion of the respective pattern oflight from the two-dimensional array of pixels to a pupil of an eye of auser (e.g., FIG. 3D). The display device also includes one or moresensors (e.g., an array of sensors) for determining a location of thepupil of the eye of the user.

In some embodiments, the display device determines (502) a location of apupil of an eye of the user. For example, the display device sendsnon-visible light (e.g., infrared light) toward the eye of the user, andcollects non-visible light that is reflected by the eye of the user.Based on an intensity profile of the light reflected by the eye of theuser, the display device determines the location of the pupil of the eyeof the user (e.g., a location with the highest intensity of thereflected light corresponds to the location of the pupil of the eye ofthe user).

In some embodiments, the display device activates (504) the one or moresensors for determining the location of the pupil of the eye of the userbetween activating the subset of the two-dimensional array of tiles(e.g., FIG. 4J). In some embodiments, the display device activates thearray of sensors for determining the location of the pupil of the eye ofthe user between activating the subset of the two-dimensional array oftiles.

In some embodiments, the display device concurrently activates (506) atleast a subset of the one or more sensors for determining the locationof the pupil of the eye of the user (e.g., FIG. 4E). In someembodiments, the display device concurrently activates (506) at least asubset of the array of sensors for determining the location of the pupilof the eye of the user. In some embodiments, the display deviceconcurrently activates a subset of the array of emitters for determiningthe location of the pupil of the eye of the user. For example, thedisplay device concurrently activates all of the emitters and detectsreflected light with the one or more sensors (e.g., the array ofsensors) for determining the location of the pupil of the eye.

In some embodiments, the display device activates (508) at least asubset of the one or more sensors (e.g., the array of sensors)sequentially for determining the location of the pupil of the eye of theuser (e.g., FIG. 4D). In some embodiments, the display device activatesa subset of the array of emitters sequentially for determining thelocation of the pupil of the eye of the user. For example, the displaydevice sequentially activates the array of emitters (in conjunction withsequentially activating the array of sensors) in a raster pattern.

In some embodiments, the display device activates a first subset of thearray of emitters concurrently for determining the location of the pupilof the eye of the user and subsequently activates a second subset of thearray of emitters sequentially for determining the location of the pupilof the eye of the user. For example, the display device activates thefirst subset of the array of emitters concurrently for determining thelocation of the pupil of the eye of the user with a first accuracy andthe display device activates the second subset of the array of emitterssequentially for determining the location of the pupil of the eye of theuser with a second accuracy that is distinct from the first accuracy.Alternatively, in some embodiments, the display device activates a firstsubset of the array of emitters sequentially for determining thelocation of the pupil of the eye of the user and subsequently activatesa second subset of the array of emitters concurrently for determiningthe location of the pupil of the eye of the user.

The display device selects (510) a subset of the two-dimensional arrayof tiles based on the location of the pupil of the eye of the user andactivates the subset of the two-dimensional array of tiles foroutputting, from at least the subset of the two-dimensional array oftiles, a collective pattern of light that is directed to the pupil ofthe eye of the user. For example, tiles that are located far from thelocation of the pupil of the eye are not selected (and as a result, thetiles that are located far from the location of the pupil of the eye arenot activated).

FIGS. 6A and 6B are partial cross-sectional views of an electro-opticelement in accordance with some embodiments.

The electro-optic element includes transparent layers 602 and 604 (e.g.,glass substrates) and liquid crystal layer 606 between transparentlayers 602 and 604. The electro-optic element also includes electrode608 (e.g., a planar electrode) on transparent layer 602 and electrodes610 and 612 (e.g., patterned electrodes) on transparent layer 604.Although two electrodes 610 and two electrodes 612 are shown in FIGS. 6Aand 6B, an electro-optic element may include three or more electrodes610 and three or more electrodes 612 (e.g., 25 electrodes). In someembodiments, electrodes 610 and 612 are masked to reduce directinteraction between light and electrodes 610 and 612.

FIG. 6A illustrates that a first voltage (e.g., 5V) is applied toelectrodes 610 and a ground voltage (e.g., 0V) is applied to electrodes612 and 608, which causes liquid crystals to align based on thedistribution of the electrical potential generated by the voltagesapplied to electrodes 608, 610, and 612.

Line 614 represents a shape of an equivalent liquid crystal prism formedby the application of the voltages to electrodes 608, 610, and 612.However, line 614 does not necessarily represent a visible feature inthe electro-optic element.

When a ray of light enters the electro-optic element from firstdirection 620, due to the alignment of the liquid crystals, thedirection of light changes to second direction 622 that is distinct fromfirst direction 620 (e.g., when the ray of light enters theelectro-optic element perpendicularly to substrate 604, the ray of lightexits from the electro-optic element at a slanted angle toward left).

FIG. 6B illustrates that the first voltage (e.g., 5V) is applied toelectrodes 612, and a ground voltage (e.g., 0V) is applied to electrodes610 and 608, which causes liquid crystals to realign based on thechanged distribution of the electrical potential generated by thevoltages applied to electrodes 608, 610, and 612.

Line 616 represents a shape of an equivalent liquid crystal prism formedby the application of the changed voltages to electrodes 608, 610, and612. The orientation of the equivalent liquid crystal prism shown inFIG. 6B is opposite to the orientation of the equivalent liquid crystalprism shown in FIG. 6A. Thus, in FIG. 6B, when a ray of light enters theelectro-optic element from first direction 620, due to the changedalignment of the liquid crystals, the direction of light changes tothird direction 624 that is distinct from first direction 620 and seconddirection 622 (e.g., when the ray of light enters the electro-opticelement perpendicularly to substrate 604, the ray of light exits fromthe electro-optic element at a slanted angle toward right).

Thus, by changing the voltages applied to electrodes 608, 610, and 612,the direction of light exiting from the electro-optic element can beadjusted (e.g., toward left or right). When no voltages are applied toelectrodes 608, 610, and 612, light exits from the electro-optic elementwithout changing its direction.

In addition, by changing the amplitude of the voltages applied toelectrodes 608, 610, and 612, the extent of changes to the direction oflight can be selected. For example, when a third voltage (e.g., 2.5V)that is lower than the first voltage (e.g., 5V) is applied to electrodes610, and a ground voltage (e.g., 0V) is applied to electrodes 612 and608, light exits from the electro-optic element at an angle (from asurface normal of substrate 602) that is smaller than the angle of light(from the surface normal of substrate 602) exiting from theelectro-optic element when the first voltage (e.g., 5V) is applied toelectrodes 610 and a ground voltage (e.g., 0V) is applied to electrodes612 and 608.

Although FIGS. 6A-6B illustrate steering a beam (or a ray) of light on asame plane (e.g., from left to right), in some embodiments, theelectro-optic element is configured to steer the beam (or the ray) oflight in two dimensions (e.g., left, right, up, down, or a diagonaldirection).

FIG. 6C is a plan view of an electro-optic element in accordance withsome embodiments.

In FIG. 6C, the electro-optic element includes a plurality of electrodes630 that are axisymmetrically arranged. For example, electrode 630 islocated in a center of the electro-optic element, surrounded by a firstgroup of electrodes 632, which are, in turn, surrounded by a secondgroup of electrodes 634, a third group of electrodes 636, a fourth groupof electrodes 638, and a fifth group of electrodes 640. By applyingdifferent voltages to different groups of electrodes, the liquidcrystals are arranged in such a way that the liquid crystalscollectively operate as a lens. By changing the amplitude of voltagesapplied to different groups of electrodes, the liquid crystals operateas a lens of a different power (e.g., a focal length of an equivalentlens changes based on the amplitude of voltages applied to differentgroups of electrodes).

FIG. 6D is a plan view of an electro-optic element in accordance withsome embodiments.

In FIG. 6D, the electro-optic lens includes a rectangular array ofelectrodes 640. By selectively applying various voltages to respectiveelectrodes 640, the liquid crystals can be arranged in such a way thatthe liquid crystals collectively operate as a lens.

FIG. 6E is a schematic diagram illustrating an exemplary operation oftiles in accordance with some embodiments. FIG. 6E is similar to FIG. 3Eexcept that electro-optic elements 600A, 600B, and 600C are used inplace of lenses 342A, 342B, and 342C shown in FIG. 3E.

As shown above, the electro-optic element can be used for directing (orsteering) light as well as focusing (or defocusing) the light. Theelectro-optic element is used in place of a lens (e.g., lens 342 in FIG.3C) or a lens assembly (e.g., lens assembly 604 in FIG. 6A) in a tile.Alternatively, the electro-optic element is used in conjunction with thelens or the lens assembly in a tile.

In some embodiments, the display device includes one or more prisms(e.g., a prism made of a cycloidal diffractive waveplate, a polarizationgrating, or a liquid crystal prism). In some embodiments, the one ormore prisms are electro-optic elements, which allowelectrically-controlled beam steering (e.g., discrete or continuous beamsteering), beam shaping, and polarization conversion. When light isdirected through the prism, the light is dispersed. In some embodiments,to correct for the dispersion, color separated images are projected bythe display device so that corresponding pixels in the color separatedimages overlap when forming an image on the retina of the eye of theuser. Thus, projecting the color separated images compensates for, orreduces the effect of, the dispersion by the prism. Accordingly, theuser will see an overlap of the color separated images as a unifiedimage.

FIG. 6F is a schematic diagram illustrating a structure of a liquidcrystal grating (e.g., a liquid crystal polarization grating) inaccordance with some embodiments. The schematic diagram shown in FIG. 6Fcorresponds to a cross-sectional view of the liquid crystal grating.

In FIG. 6F, liquid 660 containing liquid crystals (e.g., twisted nematicliquid crystals) is located between first substrate 662 and secondsubstrate 664. In some embodiments, first substrate 662 is parallel tosecond substrate 664. First substrate 662 includes one or moreelectrodes 666, and second substrate 664 includes one or more electrodes668. First substrate 662 also includes alignment layer 670, and secondsubstrate 664 includes alignment layer 672. First substrate 662 andsecond substrate 664 are made of optically transparent material (e.g.,glass, fused silica, sapphire, etc.). One or more electrodes 666 and/orone or more electrodes 668 are made with optically transparent material(e.g., indium tin oxide). Alignment layer 670 and alignment layer 672are made with optically transparent material. In some embodiments, firstsubstrate 662 and second substrate 664 are separated by 5 μm, 10 μm, 15μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 70 μm, 80μm, 90 μm, or 100 μm. In some embodiments, first substrate 662 andsecond substrate 664 are separated by a different distance.

In some embodiments, alignment layers 670 and 672 are formed bymechanical methods (e.g., rubbing, friction transfer, stretching, etc.).In some embodiments, alignment layers 670 and 672 are formed bypatterning (e.g., imprinting, ink-jet printing, exposure to an ion beam,plasma beam, or electron beam, etc.). In some embodiments, alignmentlayers 670 and 672 are self-assembled monolayers. In some embodiments,alignment layers 670 and 672 are photo-alignment layers. In someembodiments, the photo-alignment layers include linearphoto-polymerizable polymers (e.g., polyester or polyimide, etc.). Whenthe photo-alignment layers include linear photo-polymerizable polymers,the photo-alignment layers are exposed to two orthogonal circularlypolarized beams that are not parallel to each other, which create aspatially separated rotating linear polarization field. In someembodiments, the linear photo-polymerizable polymers are aligned withthe spatially separated rotating linear polarization field. In someembodiments, the two orthogonal circularly polarized beams cure thelinear photo-polymerizable polymers (e.g., the beams include ultravioletlight, which cures the polymers).

When liquid crystals are provided between two photo-alignment layers 666and 668, liquid crystals align with the spatially separated rotatinglinear polarization pattern as shown in FIG. 6G, which is a schematicdiagram illustrating the orientations of liquid crystals viewed from thetop of the liquid crystal grating in accordance with some embodiments.

FIG. 6H illustrates the orientations of liquid crystals viewed from theside of the liquid crystal grating when no voltage is applied betweenone or more electrodes 666 on first substrate 662 and one or moreelectrodes 668 on second substrate 664 (e.g., a voltage differentialapplied by voltage source 692 is zero).

FIG. 6I illustrates the orientations of liquid crystals viewed from theside of the liquid crystal grating when a voltage differential isapplied between one or more electrodes 666 on first substrate 662 andone or more electrodes 668 on second substrate 664, which create apattern of an electric field on liquid 660 (e.g., using voltage source692). As shown in FIGS. 6H and 6I, liquid crystals in liquid 660 arealigned in accordance with the electric field. For example, when noelectric field is applied (e.g., FIG. 6H), liquid crystals are alignedin first orientations (e.g., parallel to substrates 662 and 664). Whenan electric field is applied with a voltage differential, at least someof liquid crystals are aligned in different orientations. In someembodiments, when the electric field is further increased, at least someof liquid crystals are further tilted. For example, when a first voltageis applied, the liquid crystals are aligned in a first orientation; whena second voltage is applied, the liquid crystals are aligned in a secondorientation that is distinct from the first orientation; and when athird voltage is applied, the liquid crystals are aligned in a thirdorientation that is distinct from the first orientation and the secondorientation.

When circularly polarized light (e.g., with right-handed polarization)impinges on the liquid crystal polarization grating (when no voltagedifferential is applied between one or more electrodes 666 on firstsubstrate 662 and one or more electrodes 668 on second substrate 664),the transmitted light is deflected to a particular direction (e.g., adirection of a first order diffraction). When orthogonal circularlypolarized light (e.g., with left-handed polarization) impinges on theliquid crystal polarization grating (when no voltage differential isapplied between one or more electrodes 666 on first substrate 662 andone or more electrodes 668 on second substrate 664), the transmittedlight is deflected to an opposite direction (e.g., a direction of afirst order diffraction in an opposite direction). When a voltagedifferential above a threshold voltage differential is applied,circularly polarized light (e.g., with either right-handed polarizationor left-handed polarization) is transmitted through the liquid crystalpolarization grating without deflection. Thus, the liquid crystalpolarization grating functions as a beam steering device. The directionof deflection is determined by a period of the electrodes (e.g., 5 μm,5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm,etc.).

FIG. 6K illustrates the orientations of liquid crystals viewed from theside of the liquid crystal grating when no voltage is applied betweenone or more electrodes 666 on first substrate 662 and one or moreelectrodes 668 on second substrate 664 (e.g., a voltage differentialapplied by voltage source 692 is zero).

FIG. 6L illustrates the orientations of liquid crystals viewed from theside of the liquid crystal grating when a voltage differential isapplied between one or more electrodes 666 on first substrate 662 andone or more electrodes 668 on second substrate 664, which create apattern of an electric field on liquid 660 (e.g., using voltage source692). As shown in FIGS. 6K and 6L, liquid crystals in liquid 660 arealigned in accordance with the electric field. For example, when noelectric field is applied (e.g., FIG. 6K), liquid crystals are alignedin first orientations (e.g., parallel to substrates 662 and 664). Whenan electric field is applied with a voltage differential, at least someof liquid crystals are aligned in different orientations.

When circularly polarized light (e.g., with right-handed polarization)impinges on the liquid crystal polarization grating (when no voltagedifferential is applied between one or more electrodes 666 on firstsubstrate 662 and one or more electrodes 668 on second substrate 664),the transmitted light is deflected to a particular direction (e.g., adirection of a first order diffraction). When orthogonal circularlypolarized light (e.g., with left-handed polarization) impinges on theliquid crystal polarization grating (when no voltage differential isapplied between one or more electrodes 666 on first substrate 662 andone or more electrodes 668 on second substrate 664), the transmittedlight is deflected to an opposite direction (e.g., a direction of afirst order diffraction in an opposite direction). When a voltagedifferential above a threshold voltage differential is applied,circularly polarized light (e.g., with either right-handed polarizationor left-handed polarization) is transmitted through the liquid crystalpolarization grating without deflection. Thus, the liquid crystalpolarization grating functions as a beam steering device. The directionof deflection is determined by a period of the electrodes (e.g., 5 μm,5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm,etc.).

FIG. 6J is a schematic diagram illustrating chromatic dispersion in beamsteering device 680 (e.g., electro-optic element 600 shown in FIG. 6A ora liquid crystal grating shown in FIG. 6F) in accordance with someembodiments.

FIG. 6J illustrates that blue light, green light, and red light impingeon electro-optic element 680 (e.g., a beam steering device)concurrently, while a particular voltage (e.g., V₂) is applied on beamsteering device 680. In FIG. 6J, the blue light, the green light, andthe red light impinge on electro-optic element 680 at a same angle, θ₁.In some embodiments, the angle θ₁ is zero.

After the blue light, the green light, and the red light pass throughbeam steering device 680, the blue light, the green light, and the redlight are dispersed as shown in FIG. 6J. In some cases, the dispersionof light is described using the following equation: d(sin θ_(i)−sinθ_(m))=mλ, where d is a spacing between two adjacent periodic patternsformed in electro-optic element 680, θ_(i) is an incident angle, θ_(m)is an angle of maximum diffraction, λ is a wavelength of light, and m isan integer indicating an order of diffraction. As can be seen from thisequation, θ_(m) is a function of λ, and thus, the direction of thediffracted light changes as a function of wavelength. In FIG. 6J, theblue light is transmitted from beam steering device 680 at angle θ₂, thegreen light is transmitted from beam steering device 680 at angle θ₃,and the red light is transmitted from beam steering device 680 at angleθ₄.

In addition, the efficiency of diffraction changes as a function ofwavelength. When a grating that is tuned to diffract green light (e.g.,light of 550 nm wavelength) in a first order is used with light of adifferent wavelength (e.g., blue or green light), a smaller portion oflight of a different wavelength is diffracted in the first order (e.g.,the diffraction efficiency is reduced for other wavelengths). Inaddition, when a grating tuned for green light is used, an amount oflight of the different wavelength that is diffracted into a differentdirection increases (e.g., diffraction in different orders increases forother wavelengths).

FIGS. 6K-6M are schematic diagrams illustrating sequential adjustment ofdiffraction by a beam steering device in accordance with someembodiments.

FIG. 6K illustrates that a first voltage (e.g., V₁) is applied on beamsteering device 680 (e.g., electro-optic element 600 shown in FIG. 6A ora liquid crystal grating shown in FIG. 6F). FIG. 6K also illustratesthat blue light (e.g., light of 475 nm wavelength) impinges on beamsteering device 680 at angle θ₁ while the first voltage (e.g., V₁) isapplied on beam steering device 680. When the first voltage is appliedon beam steering device 680, the blue light is diffracted into angle θ₃.FIG. 6K also shows angle θ₂ that corresponds a direction of diffractedblue light when a different voltage (e.g., V₂) is applied on beamsteering device 680. Adjusting the voltage applied on beam steeringdevice 680 (e.g., from V₂ to V₁) changes the alignment of liquidcrystals in beam steering device 680, and thus, changes the angle ofdiffraction.

FIG. 6L illustrates that, subsequent to application of the first voltageon beam steering device 680, a second voltage (e.g., V₂) is applied onbeam steering device 680. FIG. 6L also illustrates that green light(e.g., light of 550 nm wavelength) impinges on beam steering device 680at angle θ₁ while the second voltage (e.g., V₂) is applied on beamsteering device 680. When the second voltage is applied on beam steeringdevice 680, the green light is diffracted into angle θ₃, which matchesthe diffraction angle of the blue light shown in FIG. 6K.

FIG. 6M illustrates that, subsequent to application of the secondvoltage on beam steering device 680, a third voltage (e.g., V₃) isapplied on beam steering device 680. FIG. 6M also illustrates that redlight (e.g., light of 650 nm wavelength) impinges on beam steeringdevice 680 at angle θ₁ while the third voltage (e.g., V₃) is applied onbeam steering device 680. When the third voltage is applied on beamsteering device 680, the red light is diffracted into angle θ₃, whichmatches the diffraction angle of the blue light shown in FIG. 6K and thediffraction angle of the green light shown in FIG. 6L. FIG. 6M alsoshows angle θ₄ that corresponds a direction of diffracted red light whena different voltage (e.g., V₂) is applied on beam steering device 680.Adjusting the voltage applied on beam steering device 680 (e.g., from V₂to V₃) changes the alignment of liquid crystals in beam steering device680, and thus, changes the angle of diffraction.

FIG. 6M also illustrates that the sequential application of the firstvoltage, the second voltage, and the third voltage repeats. Sequentialtransmission of the blue light, the green light, and the red light isalso repeated. The sequential transmission of the blue light, the greenlight, and the red light is synchronized with the sequential applicationof the first voltage, the second voltage, and the third voltage (e.g.,the blue light is transmitted when the first voltage is applied, thegreen light is transmitted when the second voltage is applied, and thered light is transmitted when the third voltage is applied).

In light of these principles, we now turn to certain embodiments.

In accordance with some embodiments, a method includes sequentiallytransmitting, through a beam steering device, light of a first color andlight of a second color that is distinct from the first color. Themethod also includes applying a first voltage to the beam steeringdevice for transmission of the light of the first color through the beamsteering device; and applying a second voltage to the beam steeringdevice for transmission of the light of the second color through thebeam steering device. For example, as shown in FIGS. 6K and 6L, light ofa first color (e.g., blue light) and light of a second color (e.g.,green light) are sequentially transmitted through beam steering device680. In FIGS. 6K and 6L, a first voltage (e.g., V₁) is applied to beamsteering device 680 for transmission of the blue light and a secondvoltage (e.g., V₂) is applied to beam steering device 680 fortransmission of the green light.

In some embodiments, the method also includes repeating sequentialtransmission of the light of the first color and the light of the secondcolor through the beam steering device (e.g., as shown in FIG. 6M, thesequential application of the first voltage and the second voltage isrepeated, and sequential transmission of the light of the first colorand the light of the second color is repeated).

In some embodiments, the beam steering device includes one or moreliquid crystal polarization gratings (e.g., see FIG. 6F).

In some embodiments, applying the first voltage to the beam steeringdevice causes liquid crystals in the beam steering device to have firstretardation for the light of the first color (e.g., liquid crystals havefirst retardation for the blue light when V₁ is applied). In someembodiments, applying the second voltage to the beam steering devicecauses the liquid crystals in the beam steering device to have the firstretardation for the light of the second color (e.g., liquid crystalshave second retardation for the green light when V₂ is applied). If V₂is applied to the beam steering device, the liquid crystals haveretardation for the blue light that is different from the firstretardation. If V₁ is applied to the beam steering device, the liquidcrystals have retardation for the green light that is different from thesecond retardation.

In some embodiments, the one or more liquid crystal polarizationgratings include nematic liquid crystals.

In some embodiments, the method includes sequentially transmitting,through the beam steering device, the light of the first color (e.g.,blue light), the light of the second color (e.g., green light), and thelight of a third color that is distinct from the first color and thesecond color (e.g., red light). In some embodiments, the method alsoincludes applying a third voltage (e.g., V₃ illustrated in FIG. 6L) tothe beam steering device for transmission of the light of the thirdcolor through the beam steering device.

In some embodiments, sequentially transmitting the light of the firstcolor, the light of the second color, and the light of the third colorthrough the beam steering device includes sequentially activating afirst subpixel that is configured to transmit the light of the firstcolor (e.g., subpixel 352 in FIG. 3B configured to transmit blue light),a second subpixel that is distinct from the first subpixel andconfigured to transmit the light of the second color (e.g., subpixel 350in FIG. 3B configured to transmit green light), and a third subpixelthat is distinct from the first subpixel and the second subpixel andconfigured to transmit the light of the third color (e.g., subpixel 348in FIG. 3B configured to transmit red light).

In some embodiments, the method includes sequentially transmitting thelight of the first color, the light of the second color, and the lightof the third color through the beam steering device includessequentially activating a first light source that is configured to emitthe light of the first color, a second light source that is distinctfrom the first light source and configured to emit the light of thesecond color, and a third light source that is distinct from the firstlight source and the second light source and configured to emit thelight of the third color. For example, the display device includes lightsources configured to generate different colors (e.g., the first lightsource configured to generate blue light, the second light sourceconfigured to generate green light, and the third light sourceconfigured to generate red light).

In some embodiments, the first light source is a first laser that isconfigured to emit the light of the first color; the second light sourceis a second laser that is configured to emit the light of the secondcolor; and the third light source is a third laser that is configured toemit the light of the third color. Light emitted by a laser has a narrowbandwidth (e.g., 10 nm or less, and typically a few nm, and sometimesdown to a single-mode linewidth, such as 0.0004 nm), which improves theperformance of the display device when used with the beam steeringdevice.

In accordance with some embodiments, a display device includes a beamsteering device (e.g., beam steering device 680 in FIG. 6K); a voltagesource (e.g., voltage source 682 in FIG. 6F); and one or more processors(e.g., processor(s) 216 in FIG. 2). The one or more processors areconfigured to, for sequential transmission of light of a first color andlight of a second color that is distinct from the first color: initiate,using the voltage source, application of a first voltage to the beamsteering device for transmission of the light of the first color throughthe beam steering device; and initiate, using the voltage source,application of a second voltage to the beam steering device fortransmission of the light of the second color through the beam steeringdevice.

In some embodiments, the one or more processors are configured to repeatinitiating application of the first voltage and initiating applicationof the second voltage.

In some embodiments, the beam steering device includes one or moreliquid crystal polarization gratings.

In some embodiments, the one or more liquid crystal polarizationgratings include nematic liquid crystals.

In some embodiments, application of the first voltage to the beamsteering device causes liquid crystals in the beam steering device tohave a first retardation for the light of the first color; andapplication of the second voltage to the beam steering device causesliquid crystals in the beam steering device to have the firstretardation for the light of the second color.

In some embodiments, the one or more processors are configured toinitiate sequential transmission, through the beam steering device, ofthe light of the first color and the light of the second color.

In some embodiments, the one or more processors are configured to:initiate sequential transmission, through the beam steering device, ofthe light of the first color, the light of the second color, and lightof a third color that is distinct from the first color and the secondcolor; and initiate, using the voltage source, application of a thirdvoltage to the beam steering device for transmission of the light of thethird color through the beam steering device.

In some embodiments, sequential transmission of the light of the firstcolor, the light of the second color, and the light of the third colorthrough the beam steering device includes sequential activation of afirst subpixel that is configured to transmit the light of the firstcolor, a second subpixel that is distinct from the first subpixel andconfigured to transmit the light of the second color, and a thirdsubpixel that is distinct from the first subpixel and the secondsubpixel and configured to transmit the light of the third color.

In some embodiments, sequential transmission of the light of the firstcolor, the light of the second color, and the light of the third colorthrough the beam steering device includes sequential activation of afirst light source that is configured to emit the light of the firstcolor, a second light source that is distinct from the first lightsource and configured to emit the light of the second color, and a thirdlight source that is distinct from the first light source and the secondlight source and configured to emit the light of the third color.

In some embodiments, the first light source is a first laser that isconfigured to emit the light of the first color; the second light sourceis a second laser that is configured to emit the light of the secondcolor; and the third light source is a third laser that is configured toemit the light of the third color.

In some embodiments, the display device is a head-mounted displaydevice.

FIG. 7 is a flow diagram illustrating method 700 of activating atwo-dimensional array of tiles based on a location of a pupil of an eyein accordance with some embodiments. Method 700 is performed at adisplay device (e.g., display device 100 in FIG. 1) comprising atwo-dimensional array of tiles (e.g., FIG. 3B). Each tile includes(e.g., FIG. 3C) a two-dimensional array of pixels (e.g., 344). Eachpixel is configured to output light so that the two-dimensional array ofpixels outputs a respective pattern of light (e.g., FIG. 3G). Each tilealso includes an electro-optic element (e.g., electro-optic element 600in FIG. 6E), of a two-dimensional array of electro-optic elements,configured to direct at least a portion of the respective pattern oflight from the two-dimensional array of pixels to a pupil of an eye of auser (e.g., FIG. 6E).

In some embodiments, the display device determines (702) a location of apupil of an eye of the user. For example, the display device sendsnon-visible light (e.g., infrared light) toward the eye of the user, andcollects non-visible light that is reflected by the eye of the user.Based on an intensity profile of the light reflected by the eye of theuser, the display device determines the location of the pupil of the eyeof the user (e.g., a location with the highest intensity of thereflected light corresponds to the location of the pupil of the eye ofthe user).

The display device directs (704) at least the portion of the respectivepattern of light from the two-dimensional array of pixels to the pupilof the eye of the user (e.g., FIG. 6E).

In some embodiments, directing at least the portion of the respectivepattern of light from the two-dimensional array of pixels to the pupilof the eye of the user includes (706) activating at least a subset ofthe two-dimensional array of electro-optic elements for directing atleast a portion of light from the two-dimensional array of tiles (e.g.,in FIG. 6E, electro-optic elements 600A and 600B are activated fordirecting light from array 344A of pixels and array 344C of pixels).

In some embodiments, the display device activates (708) theelectro-optic element for directing at least the portion of therespective pattern of light from the two-dimensional array of pixels tothe pupil of the eye of the user (e.g., voltages are applied toelectrodes of the electro-optic element for steering the light from thetwo-dimensional array of tiles as shown in FIG. 6A).

In some embodiments, the display device, in response to determining thatthe pupil of the eye of the user is located at a first location,activates (710) the electro-optic element for directing at least theportion of the respective pattern of light from the two-dimensionalarray of pixels to the first location of the pupil of the eye of theuser (e.g., FIG. 6A); and, in response to determining that the pupil ofthe eye of the user is located at a second location that is distinctfrom the first location, activates the electro-optic element fordirecting at least the portion of the respective pattern of light fromthe two-dimensional array of pixels to the second location of the pupilof the eye of the user (e.g., FIG. 6B).

In some embodiments, the display device, in response to determining thatthe pupil of the eye of the user has moved from the first location tothe second location, activates the electro-optic element for changingthe direction of at least the portion of the respective pattern of lightfrom the two-dimensional array of pixels so that at least the portion ofthe respective pattern of light from the two-dimensional array of pixelsmoves from the first location to the second location. Thus, the displaydevice displays an image that is adjusted based on a lateral movementand/or a rotation of the eye.

In some embodiments, the display device activates (712) theelectro-optic element for focusing at least the portion of therespective pattern of light from the two-dimensional array of pixelsbased on the location of the pupil of the eye of the user.

FIG. 8A is a graph illustrating a perceived resolution for a respectiveregion of a retina in accordance with some embodiments.

The retina is a light-sensitive layer located on a backside of aneyeball. An image formed on the retina is converted to physiologicalsignals (e.g., electrical and/or chemical signals), which aretransmitted to a brain. It has been observed that a certain region ofthe retina (e.g., a fovea) better perceives a high resolution image thanthe rest of the retina. The fovea is responsible for sharp centralvision, and the rest of the retina is responsible for lower resolutionperipheral vision.

FIG. 8A illustrates a prophetic example of the perceived resolution (ora relative acuity) for respective regions of the retina. In FIG. 8A, thefovea (e.g., a region that corresponds to 0 degree in the graph) has thehighest perceived resolution, and the perceived resolution decreases asa respective region is located further away from the fovea.

Thus, it is not useful to project a high resolution image over theentire area of the retina. Only the fovea and its adjacent regionbenefit from a high resolution image, because the rest of the retinacannot distinguish a high resolution image from a low resolution image.

FIG. 8B illustrates non-transformed image 802, transformed image 804,and projected image 806 in accordance with some embodiments.

Non-transformed image 802 in FIG. 8B includes an image of a person. Insome embodiments, central region 822 of non-transformed image 802 is tobe projected with high resolution, and peripheral region 812 (e.g.,shaded area within non-transformed image 802 in FIG. 8B) ofnon-transformed image 802 is to be projected with low resolution.

Central region 824 of transformed image 804 corresponds to centralregion 822 of non-transformed image 802, and peripheral region 814(e.g., shaded area within transformed image 804 in FIG. 8B) oftransformed image 804 corresponds to peripheral region 812 ofnon-transformed image 802.

Comparison of non-transformed image 802 and transformed image 804 showsthat non-transformed image 802, when projected without transformation,requires four tiles (or an area equivalent to four tiles) to projectcentral region 822 of non-transformed image 802 and 21 tiles (or an areaequivalent to 21 tiles) to project peripheral region 812 ofnon-transformed image 802, transformed image 804 requires nine tiles (oran area equivalent to nine tiles) to project central region 824 oftransformed image 804 and 16 tiles (or an area equivalent to 16 tiles)to project peripheral region 814 of transformed image 804. Inembodiments where each tile has 400 pixels, non-transformed image 802uses 1,600 pixels (=4×400 pixels) to render central region 822 andtransformed image 804 uses 3,600 pixels (=9×400 pixels) to rendercentral region 824, thereby providing a higher resolution image forcentral region 824.

Comparison of non-transformed image 802 and transformed image 804 alsoshows that region 830 of non-transformed image 802 corresponds to region834 of transformed image 804 and region 832 of non-transformed image 802corresponds to region 836 of transformed image 804. While region 830 andregion 832 in non-transformed image 802 have the same size (e.g., anarea equivalent to one tile), corresponding regions 834 and 836 havedistinct sizes (e.g., region 834 has an area larger than one tile andregion 836 has an area smaller than one tile).

When transformed image 804 is projected on a retina, central region 826and peripheral region 816 of transformed image 804 are projected withdifferent magnification. In image 806 projected on the retina, centralregion 826 is demagnified more than peripheral region 816. As a result,central region 826 has a higher pixel resolution (or a higher pixeldensity) than peripheral region 816.

FIG. 8C is a schematic diagram illustrating an exemplary operation oftiles in accordance with some embodiments.

FIG. 8C is similar to FIG. 3H except that electro-optic elements 600A,600B, 600C, 600D, and 600E are used in place of lenses 342A, 342B, 342C,342D, and 342E shown in FIG. 3H.

FIG. 8C also illustrates that portions of an image rendered bytwo-dimensional arrays of pixels 344A, 344B, and 344C are projected onregions 842A, 842B, and 842C with high resolution (e.g., a high pixeldensity). Portions of an image rendered by two-dimensional arrays ofpixels 344D and 344E are projected on regions 842D and 842E with lowresolution (e.g., a low pixel density).

Although FIGS. 8B and 8C illustrate projecting a transformed image withtwo regions (e.g., a central region and a peripheral region) with twodifferent resolutions, a person having ordinary skill in the art wouldunderstand that a non-transformed image can be divided into three ormore regions (e.g., a central region, an inner peripheral region, and anouter peripheral region) and the three or more regions can be projectedwith three or more respective resolutions. In some embodiments, theresolution varies continuously from the central region to the peripheralregion. For brevity, these details are omitted herein.

FIG. 9 is a flow diagram illustrating method 900 of projectingrespective portions of an image with different resolutions in accordancewith some embodiments. Method 900 is performed at a display device(e.g., display device 100 in FIG. 1) comprising a two-dimensional arrayof tiles (e.g., FIG. 3B). Each tile includes (e.g., FIG. 3C) atwo-dimensional array of pixels (e.g., 344). Each pixel is configured tooutput light so that the two-dimensional array of pixels outputs arespective pattern of light (e.g., FIG. 3G). Each tile also includes alens of a two-dimensional array of lenses configured to direct at leasta portion of the respective pattern of light from the two-dimensionalarray of pixels to a pupil of an eye of a user (e.g., FIG. 8C).

The device obtains (902) a transformed image (e.g., transformed image804 in FIG. 8B) for projecting a non-transformed image on a retina ofthe eye of the user. The transformed image (e.g., transformed image 804in FIG. 8B) is distinct from the non-transformed image (e.g.,non-transformed image 802 in FIG. 8B).

In some embodiments, the device receives (904) the transformed imagefrom one or more electronic devices located separately from the displaydevice (e.g., console 210 in FIG. 2).

In some embodiments, the device generates (906) the transformed imagefrom the non-transformed image. For example, the device magnifies acentral region of a non-transformed image and demagnifies a peripheralregion of a non-transformed image (e.g., the device demagnifies aperipheral region horizontally and/or vertically) to generate atransformed image, as shown in FIG. 8B.

In some embodiments, the first portion of the transformed imagecorresponds (908) to a third portion of the non-transformed image (e.g.,region 834 of transformed image 836 corresponds to region 830 ofnon-transformed image 802). The second portion of the transformed imagecorresponds to a fourth portion of the non-transformed image (e.g.,region 836 of transformed image 836 corresponds to region 832 ofnon-transformed image 802). When the third portion of thenon-transformed image and the fourth portion of the non-transformedimage have a same size (e.g., region 830 and region 832 have the samesize), the first portion of the transformed image and the second portionof the transformed image have distinct sizes (e.g., region 834 andregion 836 have different sizes).

In some embodiments, the device determines (910) a location of the pupilof the eye of the user. The transformed image corresponds to thelocation of the pupil of the eye of the user. For example, when the eyeof the user gazes a central region of the image (e.g., an upper body ofa person), the central region of the image is projected with highresolution and the rest of the image is projected with low resolution.When the eye of the user gazes a particular corner region of the image(e.g., a face of the person), the particular corner region of the imageis projected with high resolution and the rest of the image is projectedwith low resolution. Alternatively, when the eye of the user rollstoward the particular corner region of the image, the image is updatedso that the particular corner region of the image moves toward thecenter of the image. For example, when the eye of the user rolls towarda face of a person in the image, projected with low resolution, as shownin FIG. 8B, the image is updated so that the face of the person isrendered near the center of the image with high resolution. A body ofthe person, which is rendered with high resolution before the eye of theuser rolls, is rendered, after the eye rolls, off the center of theimage with low resolution.

The device activates (912) a first subset of the two-dimensional arrayof tiles for projecting a first portion of the transformed image on theretina of the eye of the user with a first resolution. For example, asshown in FIG. 8B, the device activates nine tiles for projecting centralregion 824 of transformed image 804 on the retina of the eye of the userwith high resolution.

The device activates (914) a second subset of the two-dimensional arrayof tiles, that is distinct from the first subset of the two-dimensionalarray of tiles, for projecting a second portion of the transformedimage, that is distinct from the first portion of the transformed image,on the retina of the eye of the user with a second resolution that isdistinct from the first resolution. For example, as shown in FIG. 8B,the device activates 16 tiles for projecting peripheral region 814 oftransformed image 804 on the retina of the eye of the user with lowresolution.

In some embodiments, the two-dimensional array of lenses is (916) atwo-dimensional array of electro-optic lenses (e.g., electro-opticelements 600A through 600E in FIG. 8C). The device activates a firstsubset of the two-dimensional array of electro-optic lenses forprojecting the first portion of the transformed image on a first regionof the retina of the eye (e.g., electro-optic elements 600A, 600B, and600C are activated to project central region 824 of transformed image804 on regions 842A, 842B, and 842C of the retina) and activates asecond subset of the two-dimensional array of electro-optic lenses thatis distinct from the first subset of the two-dimensional array ofelectro-optic lenses for projecting the second portion of thetransformed image on a second region of the retina of the eye that isdistinct from the first region of the retina of the eye (e.g.,electro-optic elements 600D and 600E are activated to project peripheralregion 814 of transformed image 804 on regions 842D and 842E of theretina).

In some embodiments, the first region of the retina is (918) a fovea andthe second region of the retina is a region of the retina other than thefovea (e.g., a peripheral region of the retina).

FIGS. 10A and 10B are schematic diagrams illustrating an exemplaryoperation of a tile in accordance with some embodiments.

A lower portion of FIG. 10A is similar to FIG. 6E except that onlytwo-dimensional array 344B of pixels and electro-optic element 600B areactivated (e.g., two-dimensional arrays 344A and 344C and electro-opticelements 600A and 600C are not activated to simplify the illustration).A top portion of FIG. 10A illustrates a configuration of a lens insidean eye when the eye is viewing a far object (e.g., a tree that islocated far from the eye). The lens is relaxed to focus light from thefar object on the retina of the eye.

A top portion of FIG. 10B illustrates a configuration of the lens insidethe eye when the eye is viewing an adjacent object (e.g., a newsletteror a magazine that the eye is reading). The lens changes its curvatureto focus light from the adjacent object on the retina of the eye.

A lower portion of FIG. 10B illustrates that electro-optic element 600Bis adjusted so that light from two-dimensional array 344B of pixels isprojected out of focus on the retina of the eye when the lens of eye 325is relaxed (e.g., the focal length of electro-optic element 600B isincreased so that the light from two-dimensional array 344B of pixels isfocused on plane 332B′ that is behind the retina when the lens of eye325 is relaxed). This allows the lens inside eye 325 to change itscurvature so that the light from two-dimensional array 344B of pixels isfocused on the retina of eye 325. Because a brain is trained to relaxthe lens inside the eye for viewing far objects and tighten the lensinside the eye for viewing adjacent objects, this provides natural andcomfortable user experience.

FIG. 10C is a schematic diagram illustrating a distance model inaccordance with some embodiments. Three-dimensional settings data (e.g.,a data representation of a three-dimensional environment, such as avirtual reality environment or an augmented reality environment)includes information identifying shapes and locations of objects (andoptionally their shading and/or texture information). From theinformation identifying the locations of the objects, the distance fromthe user to the object in the three-dimensional environment can bedetermined. For example, as shown in FIG. 10C, particularthree-dimensional settings data includes information representing person1002, automobile 1004, and building 1006 at respective locations. Basedon a view point (e.g., a location of eye 325 in the three-dimensionalenvironment), distances from eye 325 to person 1002, automobile 1004,and building 1006 in the three-dimensional environment are determined.

FIG. 11 is a flow diagram illustrating a method of projecting light witha focal length selected based on proximity of an object in a distancemodel in accordance with some embodiments. Method 1100 is performed at adisplay device (e.g., display device 100 in FIG. 1) comprising atwo-dimensional array of tiles (e.g., FIG. 3B). Each tile includes(e.g., FIG. 3C) a two-dimensional array of pixels (e.g., 344). Eachpixel is configured to output light so that the two-dimensional array ofpixels outputs a respective pattern of light (e.g., FIG. 3G). Each tilealso includes an electro-optic element (e.g., electro-optic element 600in FIG. 6E), of a two-dimensional array of electro-optic elements,configured to direct at least a portion of the respective pattern oflight from the two-dimensional array of pixels to a pupil of an eye of auser (e.g., FIG. 6E).

The device obtains (1102) an image of an object (e.g., a newspaper). Insome embodiments, the device obtains a location of the object in athree-dimensional model (e.g., how far the object is located from theuser in the three-dimensional model) with the image of the object.

In some embodiments, the device determines (1104) a position of thepupil of the eye; and obtains the image of the object based on theposition of the pupil of the eye. For example, the device performs ascan to determine a position of the pupil of the eye (e.g., a locationof the pupil of the eye and/or a viewing angle (or a gaze) of the eye).

In some embodiments, the display device includes one or more sensors(e.g., an array of sensors) for determining the position of the pupil ofthe eye (e.g., FIG. 4G).

The device activates (1106) at least a subset of the two-dimensionalarray of tiles for outputting, from at least the subset of thetwo-dimensional array of tiles, a collective pattern of light thatincludes at least a portion of the image of the object (e.g., a tilewith two-dimensional array 344B of pixels in FIG. 10B is activated tooutput a respective pattern of light).

The device activates (1108) at least a subset of the two-dimensionalarray of electro-optic elements for projecting the collective pattern oflight (e.g., electro-optic element 600B in FIG. 10B is activated forprojecting light from two-dimensional array 344B of pixels). At leastthe subset of the two-dimensional array of electro-optic elements isconfigured to have a focal length, that is selected based on proximityof the object in a distance model (e.g., FIG. 10C), for projecting thecollective pattern of light (e.g., when the object is located far fromthe user in the three-dimensional model, a focal length that focuses aprojected image on the retina of the eye when the lens inside the eye isrelaxed is selected, and when the objected is located adjacent to theuser in the three-dimensional model, a focal length which causes adefocused image to be projected on the retina of the eye when the lensinside the eye is relaxed is selected).

In some embodiments, the device activates at least the subset of thetwo-dimensional array of electro-optic elements for projecting thecollective pattern of light before activating at least the subset of thetwo-dimensional array of tiles for outputting, from at least the subsetof the two-dimensional array of tiles, the collective pattern of lightthat includes at least the portion of the image of the object. In someembodiments, the device activates at least the subset of thetwo-dimensional array of electro-optic elements for projecting thecollective pattern of light after activating at least the subset of thetwo-dimensional array of tiles for outputting, from at least the subsetof the two-dimensional array of tiles, the collective pattern of lightthat includes at least the portion of the image of the object. In someembodiments, the device activates at least the subset of thetwo-dimensional array of electro-optic elements for projecting thecollective pattern of light, concurrently with activating at least thesubset of the two-dimensional array of tiles for outputting, from atleast the subset of the two-dimensional array of tiles, the collectivepattern of light that includes at least the portion of the image of theobject.

In some embodiments, the device activates (1110) a first subset of thetwo-dimensional array of tiles for outputting, from at least the firstsubset of the two-dimensional array of tiles, a first collective patternof light that includes at least a portion of an image of a first object(e.g., a pattern of light that includes an image of an adjacent object);and activates a first subset of the two-dimensional array ofelectro-optic elements for projecting the first collective pattern oflight. The first subset of the two-dimensional array of electro-opticelements is configured to have a first focal length, that is selectedbased on proximity of the first object in the distance model, forprojecting the first collective pattern of light (e.g., the deviceselects a focal length, which causes a defocused image of the adjacentobject to be projected on the retina of the eye when the lens inside theeye is relaxed).

In some embodiments, the device activates (1112) a second subset of thetwo-dimensional array of tiles for outputting, from at least the secondsubset of the two-dimensional array of tiles, a second collectivepattern of light that includes at least a portion of an image of asecond object (e.g., a pattern of light that includes an image of a farobject); and activates a second subset of the two-dimensional array ofelectro-optic elements for projecting the second collective pattern oflight. The second subset of the two-dimensional array of electro-opticelements is configured to have a second focal length, that is selectedbased on proximity of the second object in the distance model, forprojecting the second collective pattern of light, and the second focallength is distinct from the first focal length (e.g., the device selectsa focal length, which causes a focused image of the far object to beprojected on the retina of the eye when the lens inside the eye isrelaxed).

In some embodiments, the first collective pattern of light and thesecond collective pattern of light are (1114) concurrently projected.For example, an image includes both a far object and an adjacent object.Some of the tiles are used to project a focused image of the far objectand a defocused image of the adjacent object at the same time when theeye is relaxed (e.g., the focused image of the far object is projectedonto a first region of the retina and the defocused image of theadjacent object is projected onto a second region of the retina that isdistinct from the first region of the retina). When the lens inside theeye is relaxed, the image of the far object projected on the firstregion of the retina remains focused and the image of the adjacentobject projected on the second region of the retina remains defocused.When the lens inside the eye is tightened (e.g., by straining ciliarymuscles connected to the lens inside the eye), the image of the farobject projected on the first region of the retina becomes defocused andthe image of the adjacent object projected on the second region of theretina becomes focused.

In some embodiments, the device, subsequent to projecting the firstcollective pattern of light while the first subset of thetwo-dimensional array of electro-optic elements is configured to havethe first focal length, determines (1116) that the proximity of thefirst object has changed in the distance model (e.g., based on imageprocessing, and/or proximity information for the object in the distancemodel, such as the three-dimensional model, received with the image ofthe object); activates a third subset of the two-dimensional array oftiles for outputting, from at least the third subset of thetwo-dimensional array of tiles, a third collective pattern of light thatincludes at least a portion of an updated image of the first object(e.g., a different number of tiles and/or pixels is used to output theupdated image, such as a zoomed-in or zoomed-out image, of the firstobject); and activates a third subset of the two-dimensional array ofelectro-optic elements for projecting the third collective pattern oflight. The third subset of the two-dimensional array of electro-opticelements is configured to have a third focal length, that is selectedbased on the changed proximity of the first object in the distancemodel, for projecting the third collective pattern of light (e.g., afocus of the updated image is changed based on the changed distancebetween the first object and the user).

Although some of various drawings illustrate a number of logical stagesin a particular order, stages which are not order dependent may bereordered and other stages may be combined or broken out. While somereordering or other groupings are specifically mentioned, others will beapparent to those of ordinary skill in the art, so the ordering andgroupings presented herein are not an exhaustive list of alternatives.Moreover, it should be recognized that the stages could be implementedin hardware, firmware, software or any combination thereof.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of the claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. For example, several of the components described herein canbe included in a single display device and several features describedherein can be implemented in the single display device. In some otherembodiments, the display device is implemented without one or morefunctions described above (e.g., the one or more processors forgoprojecting one or more portions of a transformed image and insteadproject a non-transformed image). For brevity, such details are omittedherein, because a person having ordinary skill in the art wouldrecognize various modifications based on the description in thisapplication.

The embodiments were chosen in order to best explain the principlesunderlying the claims and their practical applications, to therebyenable others skilled in the art to best use the embodiments withvarious modifications as are suited to the particular uses contemplated.

What is claimed is:
 1. A method performed by a head-mounted displaydevice that includes a beam steering device and a voltage source, themethod comprising: sequentially transmitting, through the beam steeringdevice of the head-mounted display device, light of a first color andlight of a second color that is distinct from the first color,including: applying, with the voltage source of the head-mounted displaydevice, a first voltage to the beam steering device of the head-mounteddisplay device for transmission of the light of the first color throughthe beam steering device; and applying, with the voltage source of thehead-mounted display device, a second voltage to the beam steeringdevice of the head-mounted display device for transmission of the lightof the second color through the beam steering device.
 2. The method ofclaim 1, including: repeating sequential transmission of the light ofthe first color and the light of the second color through the beamsteering device.
 3. The method of claim 1, wherein: the beam steeringdevice includes one or more liquid crystal polarization gratings.
 4. Themethod of claim 3, wherein: applying the first voltage to the beamsteering device causes liquid crystals in the beam steering device tohave first retardation for the light of the first color; and applyingthe second voltage to the beam steering device causes the liquidcrystals in the beam steering device to have the first retardation forthe light of the second color.
 5. The method of claim 3, wherein: theone or more liquid crystal polarization gratings include nematic liquidcrystals.
 6. The method of claim 1, including: sequentiallytransmitting, through the beam steering device, the light of the firstcolor, the light of the second color, and light of a third color that isdistinct from the first color and the second color; and applying a thirdvoltage to the beam steering device for transmission of the light of thethird color through the beam steering device.
 7. A method, comprising:sequentially transmitting, through a beam steering device, light of afirst color, light of a second color that is distinct from the firstcolor, and light of a third color that is distinct from the first colorand the second color, including sequentially activating a first subpixelthat is configured to transmit the light of the first color, a secondsubpixel that is distinct from the first subpixel and configured totransmit the light of the second color, and a third subpixel that isdistinct from the first subpixel and the second subpixel and configuredto transmit the light of the third color by: applying a first voltage tothe beam steering device of the head-mounted display device fortransmission of the light of the first color through the beam steeringdevice; applying a second voltage to the beam steering device of thehead-mounted display device for transmission of the light of the secondcolor through the beam steering device; and applying a third voltage tothe beam steering device of the head-mounted display device fortransmission of the light of the third color through the beam steeringdevice.
 8. The method of claim 6, including: sequentially transmittingthe light of the first color, the light of the second color, and thelight of the third color through the beam steering device includessequentially activating a first light source that is configured to emitthe light of the first color, a second light source that is distinctfrom the first light source and configured to emit the light of thesecond color, and a third light source that is distinct from the firstlight source and the second light source and configured to emit thelight of the third color.
 9. The method of claim 8, wherein: the firstlight source is a first laser that is configured to emit the light ofthe first color; the second light source is a second laser that isconfigured to emit the light of the second color; and the third lightsource is a third laser that is configured to emit the light of thethird color.
 10. A display device, comprising: a beam steering device; avoltage source; and one or more processors, wherein: the one or moreprocessors are configured to: for sequential transmission of light of afirst color and light of a second color that is distinct from the firstcolor: initiate, using the voltage source, application of a firstvoltage to the beam steering device for transmission of the light of thefirst color through the beam steering device; and initiate, using thevoltage source, application of a second voltage to the beam steeringdevice for transmission of the light of the second color through thebeam steering device; and the display device is a head-mounted displaydevice.
 11. The display device of claim 10, wherein: the beam steeringdevice includes one or more liquid crystal polarization gratings. 12.The display device of claim 11, wherein: the one or more liquid crystalpolarization gratings include nematic liquid crystals.
 13. The displaydevice of claim 11, wherein: application of the first voltage to thebeam steering device causes liquid crystals in the beam steering deviceto have a first retardation for the light of the first color; andapplication of the second voltage to the beam steering device causesliquid crystals in the beam steering device to have the firstretardation for the light of the second color.
 14. The display device ofclaim 10, wherein: the one or more processors are configured to initiatesequential transmission, through the beam steering device, of the lightof the first color and the light of the second color.
 15. The displaydevice of claim 10, wherein: the one or more processors are configuredto: initiate sequential transmission, through the beam steering device,of the light of the first color, the light of the second color, andlight of a third color that is distinct from the first color and thesecond color; and initiate, using the voltage source, application of athird voltage to the beam steering device for transmission of the lightof the third color through the beam steering device.
 16. The displaydevice of claim 15, wherein: sequential transmission of the light of thefirst color, the light of the second color, and the light of the thirdcolor through the beam steering device includes sequential activation ofa first subpixel that is configured to transmit the light of the firstcolor, a second subpixel that is distinct from the first subpixel andconfigured to transmit the light of the second color, and a thirdsubpixel that is distinct from the first subpixel and the secondsubpixel and configured to transmit the light of the third color. 17.The display device of claim 15, wherein: sequential transmission of thelight of the first color, the light of the second color, and the lightof the third color through the beam steering device includes sequentialactivation of a first light source that is configured to emit the lightof the first color, a second light source that is distinct from thefirst light source and configured to emit the light of the second color,and a third light source that is distinct from the first light sourceand the second light source and configured to emit the light of thethird color.
 18. The display device of claim 17, wherein: the firstlight source is a first laser that is configured to emit the light ofthe first color; the second light source is a second laser that isconfigured to emit the light of the second color; and the third lightsource is a third laser that is configured to emit the light of thethird color.
 19. The display device of claim 10, wherein: the one ormore processors are configured to repeat initiating application of thefirst voltage and initiating application of the second voltage.